Make Throwable/Catchable exceptions.

codegen/GenerateMain.elm

@@ -665,7 +665,7 @@ otherFile routes phaseString =
                         }
                         |> Elm.withType
                             (Gen.DataSource.annotation_.dataSource
-                                (Type.named [ "BuildError" ] "BuildError")
+                                (Type.named [ "Exception" ] "Throwable")
                                 (Gen.Server.Response.annotation_.response
                                     (Type.named [] "PageData")
                                     (Type.named [ "ErrorPage" ] "ErrorPage")
@@ -715,7 +715,7 @@ otherFile routes phaseString =
                         }
                         |> Elm.withType
                             (Gen.DataSource.annotation_.dataSource
-                                (Type.named [ "BuildError" ] "BuildError")
+                                (Type.named [ "Exception" ] "Throwable")
                                 (Gen.Server.Response.annotation_.response
                                     (Type.named [] "ActionData")
                                     (Type.named [ "ErrorPage" ] "ErrorPage")
@@ -1429,7 +1429,7 @@ otherFile routes phaseString =
                         }
                         |> Elm.withType
                             (Gen.DataSource.annotation_.dataSource
-                                (Type.named [ "BuildError" ] "BuildError")
+                                (Type.named [ "Exception" ] "Throwable")
                                 (Type.maybe Gen.Pages.Internal.NotFoundReason.annotation_.notFoundReason)
                             )
                 )
@@ -1869,7 +1869,7 @@ otherFile routes phaseString =
                         |> Gen.DataSource.call_.map Gen.List.values_.concat
                         |> Elm.withType
                             (Gen.DataSource.annotation_.dataSource
-                                (Type.named [ "BuildError" ] "BuildError")
+                                (Type.named [ "Exception" ] "Throwable")
                                 (Type.list Gen.Head.annotation_.tag)
                             )
                 )
@@ -1991,7 +1991,7 @@ otherFile routes phaseString =
                     |> Gen.DataSource.call_.map Gen.List.values_.concat
                     |> Elm.withType
                         (Gen.DataSource.annotation_.dataSource
-                            (Type.named [ "BuildError" ] "BuildError")
+                            (Type.named [ "Exception" ] "Throwable")
                             (Type.list (Type.named [ "Route" ] "Route"))
                         )
                 )

examples/docs/app/Api.elm

@@ -2,9 +2,9 @@ module Api exposing (routes)
 
 import ApiRoute
 import Article
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.Http
+import Exception exposing (Throwable)
 import Head
 import Html exposing (Html)
 import Json.Decode as Decode
@@ -21,7 +21,7 @@ import Time
 
 
 routes :
-    DataSource BuildError (List Route)
+    DataSource Throwable (List Route)
     -> (Maybe { indent : Int, newLines : Bool } -> Html Never -> String)
     -> List (ApiRoute.ApiRoute ApiRoute.Response)
 routes getStaticRoutes htmlToString =
@@ -64,7 +64,7 @@ routes getStaticRoutes htmlToString =
                             ]
                             |> Json.Encode.encode 2
                     )
-                |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                |> DataSource.throw
         )
         |> ApiRoute.literal "repo"
         |> ApiRoute.slash
@@ -105,7 +105,7 @@ routes getStaticRoutes htmlToString =
     ]
 
 
-postsDataSource : DataSource BuildError (List Rss.Item)
+postsDataSource : DataSource Throwable (List Rss.Item)
 postsDataSource =
     Article.allMetadata
         |> DataSource.map
@@ -126,7 +126,7 @@ postsDataSource =
                     }
                 )
             )
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
 
 
 rss :
@@ -136,7 +136,7 @@ rss :
     , builtAt : Time.Posix
     , indexPage : List String
     }
-    -> DataSource BuildError (List Rss.Item)
+    -> DataSource Throwable (List Rss.Item)
     -> ApiRoute.ApiRoute ApiRoute.Response
 rss options itemsRequest =
     ApiRoute.succeed

examples/docs/app/Route/Blog.elm

@@ -4,6 +4,7 @@ import Article
 import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Date
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled exposing (..)
@@ -34,10 +35,10 @@ route =
             }
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     Article.allMetadata
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
 
 
 type alias Data =

examples/docs/app/Route/Blog/Slug_.elm

@@ -7,6 +7,7 @@ import Data.Author as Author exposing (Author)
 import DataSource exposing (DataSource)
 import Date exposing (Date)
 import DateOrDateTime
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled exposing (..)
@@ -52,7 +53,7 @@ route =
         |> RouteBuilder.buildNoState { view = view }
 
 
-pages : DataSource BuildError (List RouteParams)
+pages : DataSource Throwable (List RouteParams)
 pages =
     Article.blogPostsGlob
         |> DataSource.map
@@ -240,7 +241,7 @@ type alias ActionData =
     {}
 
 
-data : RouteParams -> DataSource BuildError Data
+data : RouteParams -> DataSource Throwable Data
 data routeParams =
     MarkdownCodec.withFrontmatter Data
         frontmatterDecoder

examples/docs/app/Route/Docs/Section__.elm

@@ -1,12 +1,12 @@
 module Route.Docs.Section__ exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import Css
 import Css.Global
 import DataSource exposing (DataSource)
 import DataSource.File
 import DataSource.Glob as Glob exposing (Glob)
 import DocsSection exposing (Section)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Heroicon
@@ -55,7 +55,7 @@ route =
             }
 
 
-pages : DataSource BuildError (List RouteParams)
+pages : DataSource Throwable (List RouteParams)
 pages =
     DocsSection.all
         |> DataSource.map
@@ -70,7 +70,7 @@ pages =
             )
 
 
-data : RouteParams -> DataSource BuildError Data
+data : RouteParams -> DataSource Throwable Data
 data routeParams =
     DataSource.map4 Data
         (pageBody routeParams)
@@ -80,7 +80,7 @@ data routeParams =
             |> findBySlug
             |> Glob.expectUniqueMatch
             |> DataSource.map filePathToEditUrl
-            |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+            |> DataSource.throw
         )
         (routeParams |> filePathDataSource |> DataSource.andThen MarkdownCodec.titleAndDescription)
 
@@ -90,7 +90,7 @@ filePathToEditUrl filePath =
     "https://github.com/dillonkearns/elm-pages/edit/master/examples/docs/" ++ filePath
 
 
-previousAndNextData : RouteParams -> DataSource BuildError { title : String, previousAndNext : ( Maybe NextPrevious.Item, Maybe NextPrevious.Item ) }
+previousAndNextData : RouteParams -> DataSource Throwable { title : String, previousAndNext : ( Maybe NextPrevious.Item, Maybe NextPrevious.Item ) }
 previousAndNextData current =
     DocsSection.all
         |> DataSource.andThen
@@ -105,7 +105,7 @@ previousAndNextData current =
                 DataSource.map2 (\title previousAndNext -> { title = title, previousAndNext = previousAndNext })
                     (List.Extra.getAt index sections
                         |> maybeDataSource titleForSection
-                        |> DataSource.map (Result.fromMaybe (BuildError.internal "Couldn't find section"))
+                        |> DataSource.map (Result.fromMaybe (Exception.fromString "Couldn't find section"))
                         |> DataSource.andThen DataSource.fromResult
                         |> DataSource.map .title
                     )
@@ -130,14 +130,14 @@ maybeDataSource fn maybe =
             DataSource.succeed Nothing
 
 
-titleForSection : Section -> DataSource BuildError NextPrevious.Item
+titleForSection : Section -> DataSource Throwable NextPrevious.Item
 titleForSection section =
     Glob.expectUniqueMatch (findBySlug section.slug)
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
         |> DataSource.andThen
             (\filePath ->
                 DataSource.File.bodyWithoutFrontmatter filePath
-                    |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                    |> DataSource.throw
                     |> DataSource.andThen markdownBodyDecoder2
                     |> DataSource.map
                         (\blocks ->
@@ -159,7 +159,7 @@ titleForSection section =
         |> DataSource.andThen
             (\maybeTitle ->
                 maybeTitle
-                    |> Result.fromMaybe (BuildError.internal "Expected to find an H1 heading in this markdown.")
+                    |> Result.fromMaybe (Exception.fromString "Expected to find an H1 heading in this markdown.")
                     |> DataSource.fromResult
             )
 
@@ -285,7 +285,7 @@ view maybeUrl sharedModel static =
     }
 
 
-filePathDataSource : RouteParams -> DataSource BuildError String
+filePathDataSource : RouteParams -> DataSource Throwable String
 filePathDataSource routeParams =
     let
         slug : String
@@ -294,10 +294,10 @@ filePathDataSource routeParams =
                 |> Maybe.withDefault "what-is-elm-pages"
     in
     Glob.expectUniqueMatch (findBySlug slug)
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
 
 
-pageBody : RouteParams -> DataSource BuildError (List Block)
+pageBody : RouteParams -> DataSource Throwable (List Block)
 pageBody routeParams =
     routeParams
         |> filePathDataSource
@@ -316,9 +316,9 @@ findBySlug slug =
         |> Glob.match (Glob.literal ".md")
 
 
-markdownBodyDecoder2 : String -> DataSource BuildError (List Block)
+markdownBodyDecoder2 : String -> DataSource Throwable (List Block)
 markdownBodyDecoder2 rawBody =
     rawBody
         |> Markdown.Parser.parse
-        |> Result.mapError (\_ -> BuildError.internal "Markdown parsing error")
+        |> Result.mapError (\_ -> Exception.fromString "Markdown parsing error")
         |> DataSource.fromResult

examples/docs/app/Route/Index.elm

@@ -1,8 +1,8 @@
 module Route.Index exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import Css
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html exposing (..)
@@ -86,7 +86,7 @@ view maybeUrl sharedModel static =
     }
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.succeed ()
 

examples/docs/app/Route/Showcase.elm

@@ -1,8 +1,8 @@
 module Route.Showcase exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import Css
 import DataSource exposing (DataSource)
+import Exception exposing (Catchable, Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled exposing (..)
@@ -40,7 +40,7 @@ route =
         |> RouteBuilder.buildNoState { view = view }
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     Showcase.staticRequest
 

examples/docs/app/Shared.elm

@@ -1,9 +1,9 @@
 module Shared exposing (Data, Model, Msg, template)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DocsSection
 import Effect exposing (Effect)
+import Exception exposing (Throwable)
 import Html exposing (Html)
 import Html.Styled
 import Pages.Flags
@@ -86,7 +86,7 @@ subscriptions _ _ =
     Sub.none
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     TableOfContents.dataSource DocsSection.all
 

examples/docs/app/Site.elm

@@ -1,8 +1,8 @@
 module Site exposing (canonicalUrl, config)
 
-import BuildError exposing (BuildError)
 import Cloudinary
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import MimeType
 import Pages.Url
@@ -16,7 +16,7 @@ config =
     }
 
 
-head : DataSource BuildError (List Head.Tag)
+head : DataSource Throwable (List Head.Tag)
 head =
     [ Head.metaName "viewport" (Head.raw "width=device-width,initial-scale=1")
     , Head.metaName "mobile-web-app-capable" (Head.raw "yes")

examples/docs/src/Article.elm

@@ -5,6 +5,7 @@ import DataSource
 import DataSource.File as File
 import DataSource.Glob as Glob
 import Date exposing (Date)
+import Exception exposing (Catchable, Throwable)
 import Json.Decode as Decode exposing (Decoder)
 import Pages.Url exposing (Url)
 import Route
@@ -26,7 +27,7 @@ blogPostsGlob =
         |> Glob.toDataSource
 
 
-allMetadata : DataSource.DataSource (File.FileReadError Decode.Error) (List ( Route.Route, ArticleMetadata ))
+allMetadata : DataSource.DataSource (Catchable (File.FileReadError Decode.Error)) (List ( Route.Route, ArticleMetadata ))
 allMetadata =
     blogPostsGlob
         |> DataSource.map

examples/docs/src/DocsSection.elm

@@ -12,7 +12,7 @@ type alias Section =
     }
 
 
-all : DataSource BuildError (List Section)
+all : DataSource error (List Section)
 all =
     Glob.succeed Section
         |> Glob.captureFilePath

examples/docs/src/Manifest.elm

@@ -1,6 +1,5 @@
 module Manifest exposing (config)
 
-import BuildError exposing (BuildError)
 import Cloudinary
 import DataSource exposing (DataSource)
 import MimeType
@@ -9,7 +8,7 @@ import Pages.Url
 import Route
 
 
-config : DataSource BuildError Manifest.Config
+config : DataSource error Manifest.Config
 config =
     Manifest.init
         { name = "elm-pages"

examples/docs/src/Showcase.elm

@@ -4,6 +4,7 @@ import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.Env as Env
 import DataSource.Http
+import Exception exposing (Throwable)
 import Json.Decode as Decode exposing (Decoder)
 import Json.Decode.Extra
 
@@ -38,10 +39,10 @@ entryDecoder =
             (Decode.maybe (Decode.field "Repository URL" Decode.string))
 
 
-staticRequest : DataSource BuildError (List Entry)
+staticRequest : DataSource Throwable (List Entry)
 staticRequest =
     Env.expect "AIRTABLE_TOKEN"
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
         |> DataSource.andThen
             (\airtableToken ->
                 DataSource.Http.request
@@ -51,7 +52,7 @@ staticRequest =
                     , body = DataSource.Http.emptyBody
                     }
                     (DataSource.Http.expectJson decoder)
-                    |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                    |> DataSource.throw
             )
 
 

examples/docs/src/TableOfContents.elm

@@ -1,9 +1,9 @@
 module TableOfContents exposing (..)
 
-import BuildError exposing (BuildError)
 import Css
 import DataSource exposing (DataSource)
 import DataSource.File
+import Exception exposing (Throwable)
 import Html.Styled exposing (..)
 import Html.Styled.Attributes as Attr exposing (css)
 import List.Extra
@@ -14,8 +14,8 @@ import Tailwind.Utilities as Tw
 
 
 dataSource :
-    DataSource BuildError (List { file | filePath : String, slug : String })
+    DataSource Throwable (List { file | filePath : String, slug : String })
-    -> DataSource BuildError (TableOfContents Data)
+    -> DataSource Throwable (TableOfContents Data)
 dataSource docFiles =
     docFiles
         |> DataSource.map
@@ -25,20 +25,20 @@ dataSource docFiles =
                         (\section ->
                             DataSource.File.bodyWithoutFrontmatter
                                 section.filePath
-                                |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                                |> DataSource.throw
                                 |> DataSource.andThen (headingsDecoder section.slug)
                         )
             )
         |> DataSource.resolve
 
 
-headingsDecoder : String -> String -> DataSource BuildError (Entry Data)
+headingsDecoder : String -> String -> DataSource Throwable (Entry Data)
 headingsDecoder slug rawBody =
     rawBody
         |> Markdown.Parser.parse
-        |> Result.mapError (\_ -> BuildError.internal "Markdown parsing error")
+        |> Result.mapError (\_ -> Exception.fromString "Markdown parsing error")
         |> Result.map gatherHeadings
-        |> Result.andThen (nameAndTopLevel slug >> Result.mapError BuildError.internal)
+        |> Result.andThen (nameAndTopLevel slug >> Result.mapError Exception.fromString)
         |> DataSource.fromResult
 
 

examples/end-to-end/app/Api.elm

@@ -1,8 +1,8 @@
 module Api exposing (routes)
 
 import ApiRoute exposing (ApiRoute)
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Form
 import Form.Field as Field
 import Form.Validation as Validation
@@ -22,7 +22,7 @@ import Xml.Decode
 
 
 routes :
-    DataSource BuildError (List Route)
+    DataSource Throwable (List Route)
     -> (Maybe { indent : Int, newLines : Bool } -> Html Never -> String)
     -> List (ApiRoute.ApiRoute ApiRoute.Response)
 routes getStaticRoutes htmlToString =

examples/end-to-end/app/Route/Blog/Slug_.elm

@@ -1,7 +1,7 @@
 module Route.Blog.Slug_ exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Pages.Msg
@@ -38,7 +38,7 @@ route =
         |> RouteBuilder.buildNoState { view = view }
 
 
-pages : DataSource BuildError (List RouteParams)
+pages : DataSource Throwable (List RouteParams)
 pages =
     DataSource.succeed []
 
@@ -47,7 +47,7 @@ type alias Data =
     {}
 
 
-data : RouteParams -> DataSource BuildError Data
+data : RouteParams -> DataSource Throwable Data
 data routeParams =
     DataSource.succeed {}
 

examples/end-to-end/app/Route/CookieTest.elm

@@ -1,14 +1,12 @@
 module Route.CookieTest exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
-import Head.Seo as Seo
 import Html.Styled exposing (text)
 import Pages.Msg
 import Pages.PageUrl exposing (PageUrl)
-import Pages.Url
 import RouteBuilder exposing (StatefulRoute, StatelessRoute, StaticPayload)
 import Server.Request as Request exposing (Parser)
 import Server.Response as Response exposing (Response)
@@ -46,7 +44,7 @@ type alias Data =
     { darkMode : Maybe String }
 
 
-data : RouteParams -> Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.oneOf
         [ Request.expectCookie "dark-mode"

examples/end-to-end/app/Route/Counter.elm

@@ -1,9 +1,8 @@
 module Route.Counter exposing (ActionData, Data, Model, Msg, route)
 
-import Browser.Navigation
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Effect exposing (Effect)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html
@@ -86,7 +85,7 @@ type alias Data =
     {}
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.succeed Data
 

examples/end-to-end/app/Route/DarkMode.elm

@@ -2,11 +2,11 @@ module Route.DarkMode exposing (..)
 
 {-| -}
 
-import BuildError exposing (BuildError)
 import Css
 import DataSource exposing (DataSource)
 import Effect
 import ErrorPage
+import Exception exposing (Throwable)
 import Form
 import Form.Field as Field
 import Form.Validation as Validation
@@ -102,7 +102,7 @@ sessionOptions =
 
 data :
     RouteParams
-    -> Server.Request.Parser (DataSource BuildError (Server.Response.Response Data ErrorPage.ErrorPage))
+    -> Server.Request.Parser (DataSource Throwable (Server.Response.Response Data ErrorPage.ErrorPage))
 data routeParams =
     Server.Request.succeed ()
         |> Session.withSession sessionOptions
@@ -128,7 +128,7 @@ data routeParams =
 
 action :
     RouteParams
-    -> Server.Request.Parser (DataSource BuildError (Server.Response.Response ActionData ErrorPage.ErrorPage))
+    -> Server.Request.Parser (DataSource Throwable (Server.Response.Response ActionData ErrorPage.ErrorPage))
 action routeParams =
     Server.Request.formData
         (form

examples/end-to-end/app/Route/Fetcher.elm

@@ -2,12 +2,12 @@ module Route.Fetcher exposing (ActionData, Data, Model, Msg, RouteParams, route)
 
 {-| -}
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.Port
 import Dict
 import Effect
 import ErrorPage
+import Exception exposing (Throwable)
 import Form
 import Form.Field as Field
 import Form.FieldView as FieldView
@@ -94,7 +94,7 @@ type alias ActionData =
 
 data :
     RouteParams
-    -> Server.Request.Parser (DataSource BuildError (Server.Response.Response Data ErrorPage.ErrorPage))
+    -> Server.Request.Parser (DataSource Throwable (Server.Response.Response Data ErrorPage.ErrorPage))
 data routeParams =
     Server.Request.succeed
         (DataSource.Port.get "getItems"
@@ -116,7 +116,7 @@ type Action
 
 action :
     RouteParams
-    -> Server.Request.Parser (DataSource BuildError (Server.Response.Response ActionData ErrorPage.ErrorPage))
+    -> Server.Request.Parser (DataSource Throwable (Server.Response.Response ActionData ErrorPage.ErrorPage))
 action routeParams =
     Server.Request.formData
         forms

examples/end-to-end/app/Route/FileData.elm

@@ -3,6 +3,7 @@ module Route.FileData exposing (ActionData, Data, Model, Msg, route)
 import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.File
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled exposing (text)
@@ -45,11 +46,11 @@ type alias Data =
     }
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     "my-json-data.json"
         |> DataSource.File.jsonFile (Decode.field "greeting" Decode.string)
-        |> DataSource.mapError DataSource.File.toBuildError
+        |> DataSource.throw
         |> DataSource.map Data
 
 

examples/end-to-end/app/Route/Form.elm

@@ -1,10 +1,9 @@
 module Route.Form exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Date exposing (Date)
-import Dict
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Form
 import Form.Field as Field
 import Form.FieldView
@@ -15,11 +14,9 @@ import Head.Seo as Seo
 import Html exposing (Html)
 import Html.Attributes as Attr
 import Html.Styled
-import Html.Styled.Attributes as StyledAttr
 import Pages.Msg
 import Pages.PageUrl exposing (PageUrl)
 import Pages.Url
-import Route
 import RouteBuilder exposing (StatelessRoute, StaticPayload)
 import Server.Request as Request exposing (Parser)
 import Server.Response
@@ -188,7 +185,7 @@ type alias Data =
     {}
 
 
-data : RouteParams -> Parser (DataSource BuildError (Server.Response.Response Data ErrorPage))
+data : RouteParams -> Parser (DataSource Throwable (Server.Response.Response Data ErrorPage))
 data routeParams =
     Data
         |> Server.Response.render
@@ -196,7 +193,7 @@ data routeParams =
         |> Request.succeed
 
 
-action : RouteParams -> Parser (DataSource BuildError (Server.Response.Response ActionData ErrorPage))
+action : RouteParams -> Parser (DataSource Throwable (Server.Response.Response ActionData ErrorPage))
 action routeParams =
     Request.formData (form |> Form.initCombined identity)
         |> Request.map

examples/end-to-end/app/Route/Greet.elm

@@ -1,14 +1,13 @@
 module Route.Greet exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Effect exposing (Effect)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html exposing (Html)
 import Html.Styled.Attributes as Attr
-import Html.Styled.Events exposing (onSubmit)
 import MySession
 import Pages.Msg
 import Pages.PageUrl exposing (PageUrl)
@@ -82,7 +81,7 @@ type alias Data =
     }
 
 
-data : RouteParams -> Request.Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Request.Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.oneOf
         [ Request.map2 (\a b -> Data a b Nothing)

examples/end-to-end/app/Route/Hello.elm

@@ -1,8 +1,8 @@
 module Route.Hello exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Pages.Msg
@@ -45,7 +45,7 @@ type alias Data =
     {}
 
 
-data : RouteParams -> Request.Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Request.Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.succeed (DataSource.succeed (Response.render Data))
 

examples/end-to-end/app/Route/Index.elm

@@ -1,9 +1,9 @@
 module Route.Index exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.File
 import DataSource.Port
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled exposing (a, div, text)
@@ -49,10 +49,10 @@ type alias Data =
     }
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.map2 Data
-        (DataSource.File.rawFile "greeting.txt" |> DataSource.mapError DataSource.File.toBuildError)
+        (DataSource.File.rawFile "greeting.txt" |> DataSource.throw)
         (DataSource.Port.get "hello" (Encode.string "Jane") Decode.string)
 
 

examples/end-to-end/app/Route/Links.elm

@@ -1,7 +1,7 @@
 module Route.Links exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html exposing (text)
@@ -43,7 +43,7 @@ type alias Data =
     ()
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.succeed ()
 

examples/end-to-end/app/Route/Login.elm

@@ -1,8 +1,8 @@
 module Route.Login exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Form
 import Form.Field as Field
 import Form.FieldView
@@ -51,7 +51,7 @@ route =
         |> RouteBuilder.buildNoState { view = view }
 
 
-action : RouteParams -> Request.Parser (DataSource BuildError (Response ActionData ErrorPage))
+action : RouteParams -> Request.Parser (DataSource Throwable (Response ActionData ErrorPage))
 action routeParams =
     Request.formDataWithServerValidation (form |> Form.initCombinedServer identity)
         |> MySession.withSession
@@ -162,7 +162,7 @@ form =
         |> Form.field "name" (Field.text |> Field.required "Required")
 
 
-data : RouteParams -> Request.Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Request.Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.oneOf
         [ Request.succeed ()

examples/end-to-end/app/Route/Logout.elm

@@ -1,8 +1,8 @@
 module Route.Logout exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import MySession
@@ -44,7 +44,7 @@ route =
         |> RouteBuilder.buildNoState { view = view }
 
 
-action : RouteParams -> Request.Parser (DataSource BuildError (Response ActionData ErrorPage))
+action : RouteParams -> Request.Parser (DataSource Throwable (Response ActionData ErrorPage))
 action _ =
     Request.succeed ()
         |> MySession.withSession
@@ -61,7 +61,7 @@ type alias Data =
     {}
 
 
-data : RouteParams -> Request.Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Request.Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.succeed (DataSource.succeed (Response.render {}))
 

examples/end-to-end/app/Route/Redirect.elm

@@ -1,12 +1,10 @@
 module Route.Redirect exposing (ActionData, Data, Model, Msg, route)
 
-import Browser.Navigation
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Effect exposing (Effect)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Form.FormData exposing (Method(..))
-import FormDecoder
 import Head
 import Head.Seo as Seo
 import Pages.Msg
@@ -94,7 +92,7 @@ type alias Data =
     {}
 
 
-data : RouteParams -> Request.Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Request.Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.oneOf
         [ Request.acceptMethod ( Request.Post, [] )

examples/end-to-end/app/Route/Test/BasicAuth.elm

@@ -1,9 +1,9 @@
 module Route.Test.BasicAuth exposing (ActionData, Data, Model, Msg, route)
 
 import Base64
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Html.Styled exposing (div, text)
 import Pages.Msg
@@ -46,7 +46,7 @@ type alias Data =
     }
 
 
-data : RouteParams -> Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     withBasicAuth
         (\{ username, password } ->

examples/end-to-end/app/Route/Test/ResponseHeaders.elm

@@ -1,10 +1,10 @@
 module Route.Test.ResponseHeaders exposing (ActionData, Data, Model, Msg, route)
 
-import Base64
 import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.File
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Html.Styled exposing (div, text)
 import Pages.Msg
@@ -47,11 +47,11 @@ type alias Data =
     }
 
 
-data : RouteParams -> Parser (DataSource BuildError (Response Data ErrorPage))
+data : RouteParams -> Parser (DataSource Throwable (Response Data ErrorPage))
 data routeParams =
     Request.succeed
         (DataSource.succeed Data
-            |> DataSource.andMap (DataSource.File.rawFile "greeting.txt" |> DataSource.mapError DataSource.File.toBuildError)
+            |> DataSource.andMap (DataSource.File.rawFile "greeting.txt" |> DataSource.throw)
             |> DataSource.map Response.render
             |> DataSource.map (Response.withHeader "x-powered-by" "my-framework")
         )

examples/end-to-end/app/Shared.elm

@@ -1,8 +1,8 @@
 module Shared exposing (Data, Model, Msg(..), SharedMsg(..), template)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Effect exposing (Effect)
+import Exception exposing (Throwable)
 import Html exposing (Html)
 import Html.Styled
 import Pages.Flags
@@ -76,7 +76,7 @@ subscriptions _ _ =
     Sub.none
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.succeed ()
 

examples/end-to-end/app/Site.elm

@@ -1,7 +1,7 @@
 module Site exposing (config)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Pages.Manifest as Manifest
 import Route
@@ -19,7 +19,7 @@ config =
     }
 
 
-head : DataSource BuildError (List Head.Tag)
+head : DataSource Throwable (List Head.Tag)
 head =
     [ Head.metaName "viewport" (Head.raw "width=device-width,initial-scale=1")
     , Head.metaName "mobile-web-app-capable" (Head.raw "yes")

examples/end-to-end/src/MySession.elm

@@ -1,12 +1,12 @@
 module MySession exposing (..)
 
-import BuildError exposing (BuildError)
 import Codec
 import DataSource exposing (DataSource)
 import DataSource.Env as Env
+import Exception exposing (Throwable)
 import Route
 import Server.Request exposing (Parser)
-import Server.Response as Response exposing (Response)
+import Server.Response exposing (Response)
 import Server.Session as Session
 import Server.SetCookie as SetCookie
 
@@ -19,9 +19,9 @@ cookieOptions =
 
 
 withSession :
-    (request -> Result Session.NotLoadedReason Session.Session -> DataSource BuildError ( Session.Session, Response data errorPage ))
+    (request -> Result Session.NotLoadedReason Session.Session -> DataSource Throwable ( Session.Session, Response data errorPage ))
     -> Parser request
-    -> Parser (DataSource BuildError (Response data errorPage))
+    -> Parser (DataSource Throwable (Response data errorPage))
 withSession =
     Session.withSession
         { name = "mysession"
@@ -31,9 +31,9 @@ withSession =
 
 
 withSessionOrRedirect :
-    (request -> Session.Session -> DataSource BuildError ( Session.Session, Response data errorPage ))
+    (request -> Session.Session -> DataSource Throwable ( Session.Session, Response data errorPage ))
     -> Parser request
-    -> Parser (DataSource BuildError (Response data errorPage))
+    -> Parser (DataSource Throwable (Response data errorPage))
 withSessionOrRedirect toRequest handler =
     Session.withSession
         { name = "mysession"
@@ -53,17 +53,17 @@ withSessionOrRedirect toRequest handler =
         handler
 
 
-secrets : DataSource BuildError (List String)
+secrets : DataSource Throwable (List String)
 secrets =
     Env.expect "SESSION_SECRET"
+        |> DataSource.throw
         |> DataSource.map List.singleton
-        |> DataSource.mapError Env.toBuildError
 
 
 expectSessionOrRedirect :
-    (request -> Session.Session -> DataSource BuildError ( Session.Session, Response data errorPage ))
+    (request -> Session.Session -> DataSource Throwable ( Session.Session, Response data errorPage ))
     -> Parser request
-    -> Parser (DataSource BuildError (Response data errorPage))
+    -> Parser (DataSource Throwable (Response data errorPage))
 expectSessionOrRedirect toRequest handler =
     Session.withSession
         { name = "mysession"

examples/escaping/app/Route/Escaping.elm

@@ -1,10 +1,10 @@
 module Route.Escaping exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import Css exposing (..)
 import Css.Global
 import DataSource exposing (DataSource)
 import DataSource.File
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html exposing (..)
@@ -48,10 +48,10 @@ type alias Data =
     String
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.File.rawFile "unsafe-script-tag.txt"
-        |> DataSource.mapError DataSource.File.toBuildError
+        |> DataSource.throw
 
 
 head :

examples/escaping/app/Route/Index.elm

@@ -1,8 +1,7 @@
 module Route.Index exposing (ActionData, Data, Model, Msg, route)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
-import DataSource.File
+import Exception exposing (Throwable)
 import Head
 import Head.Seo as Seo
 import Html.Styled as Html exposing (text)
@@ -44,7 +43,7 @@ type alias Data =
     ()
 
 
-data : DataSource BuildError Data
+data : DataSource Throwable Data
 data =
     DataSource.succeed ()
 

examples/escaping/src/Api.elm

@@ -1,14 +1,14 @@
 module Api exposing (routes)
 
 import ApiRoute
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Html exposing (Html)
 import Route exposing (Route)
 
 
 routes :
-    DataSource BuildError (List Route)
+    DataSource Throwable (List Route)
     -> (Maybe { indent : Int, newLines : Bool } -> Html Never -> String)
     -> List (ApiRoute.ApiRoute ApiRoute.Response)
 routes getStaticRoutes htmlToString =

examples/escaping/src/Shared.elm

@@ -1,8 +1,8 @@
 module Shared exposing (Data, Model, Msg(..), SharedMsg(..), template)
 
-import BuildError exposing (BuildError)
 import DataSource
 import Effect exposing (Effect)
+import Exception exposing (Throwable)
 import Html exposing (Html)
 import Html.Styled
 import Pages.Flags
@@ -76,7 +76,7 @@ subscriptions _ _ =
     Sub.none
 
 
-data : DataSource.DataSource BuildError Data
+data : DataSource.DataSource Throwable Data
 data =
     DataSource.succeed ()
 

examples/escaping/src/Site.elm

@@ -1,8 +1,8 @@
 module Site exposing (config)
 
-import BuildError exposing (BuildError)
 import Cloudinary
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import MimeType
 import Pages.Manifest as Manifest
@@ -23,14 +23,14 @@ type alias Data =
     }
 
 
-data : DataSource.DataSource BuildError Data
+data : DataSource.DataSource Throwable Data
 data =
     DataSource.map Data
         --(StaticFile.request "site-name.txt" StaticFile.body)
         (DataSource.succeed "site-name")
 
 
-head : DataSource BuildError (List Head.Tag)
+head : DataSource Throwable (List Head.Tag)
 head =
     [ Head.metaName "viewport" (Head.raw "width=device-width,initial-scale=1")
     , Head.metaName "mobile-web-app-capable" (Head.raw "yes")

generator/dead-code-review/src/Pages/Review/DeadCodeEliminateData.elm

@@ -134,8 +134,8 @@ declarationVisitor node context =
                                                 -- TODO need to replace `action` as well
                                                 [ ("data = "
                                                     ++ referenceFunction context.importContext ( [ "DataSource" ], "fail" )
-                                                    -- TODO add `import BuildError` if not present (and use alias if present)
+                                                    -- TODO add `import Exception` if not present (and use alias if present)
-                                                    ++ " (BuildError.internal \"\")\n    "
+                                                    ++ " (Exception.fromString \"\")\n    "
                                                   )
                                                     |> Review.Fix.replaceRangeBy (Node.range dataValue)
                                                 ]
@@ -193,12 +193,12 @@ expressionVisitor node context =
                                                     "preRender" ->
                                                         "\\_ -> "
                                                             ++ referenceFunction context.importContext ( [ "DataSource" ], "fail" )
-                                                            ++ " (BuildError.internal \"\")"
+                                                            ++ " (Exception.fromString \"\")"
 
                                                     "preRenderWithFallback" ->
                                                         "\\_ -> "
                                                             ++ referenceFunction context.importContext ( [ "DataSource" ], "fail" )
-                                                            ++ " (BuildError.internal \"\")"
+                                                            ++ " (Exception.fromString \"\")"
 
                                                     "serverRender" ->
                                                         "\\_ -> "
@@ -207,7 +207,7 @@ expressionVisitor node context =
 
                                                     "single" ->
                                                         referenceFunction context.importContext ( [ "DataSource" ], "fail" )
-                                                            ++ " (BuildError.internal \"\")\n       "
+                                                            ++ " (Exception.fromString \"\")\n       "
 
                                                     _ ->
                                                         "data"

generator/src/RouteBuilder.elm

@@ -85,11 +85,11 @@ When there are Dynamic Route Segments, you need to tell `elm-pages` which pages
 
 -}
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Dict exposing (Dict)
 import Effect exposing (Effect)
 import ErrorPage exposing (ErrorPage)
+import Exception exposing (Throwable)
 import Head
 import Http
 import Json.Decode
@@ -109,9 +109,9 @@ import View exposing (View)
 
 {-| -}
 type alias StatefulRoute routeParams data action model msg =
-    { data : Json.Decode.Value -> routeParams -> DataSource BuildError (Server.Response.Response data ErrorPage)
+    { data : Json.Decode.Value -> routeParams -> DataSource Throwable (Server.Response.Response data ErrorPage)
-    , action : Json.Decode.Value -> routeParams -> DataSource BuildError (Server.Response.Response action ErrorPage)
+    , action : Json.Decode.Value -> routeParams -> DataSource Throwable (Server.Response.Response action ErrorPage)
-    , staticRoutes : DataSource BuildError (List routeParams)
+    , staticRoutes : DataSource Throwable (List routeParams)
     , view :
         Maybe PageUrl
         -> Shared.Model
@@ -124,7 +124,7 @@ type alias StatefulRoute routeParams data action model msg =
     , init : Maybe PageUrl -> Shared.Model -> StaticPayload data action routeParams -> ( model, Effect msg )
     , update : PageUrl -> StaticPayload data action routeParams -> msg -> model -> Shared.Model -> ( model, Effect msg, Maybe Shared.Msg )
     , subscriptions : Maybe PageUrl -> routeParams -> Path -> model -> Shared.Model -> Sub msg
-    , handleRoute : { moduleName : List String, routePattern : RoutePattern } -> (routeParams -> List ( String, String )) -> routeParams -> DataSource BuildError (Maybe NotFoundReason)
+    , handleRoute : { moduleName : List String, routePattern : RoutePattern } -> (routeParams -> List ( String, String )) -> routeParams -> DataSource Throwable (Maybe NotFoundReason)
     , kind : String
     , onAction : Maybe (action -> msg)
     }
@@ -154,9 +154,9 @@ type alias StaticPayload data action routeParams =
 {-| -}
 type Builder routeParams data action
     = WithData
-        { data : Json.Decode.Value -> routeParams -> DataSource BuildError (Server.Response.Response data ErrorPage)
+        { data : Json.Decode.Value -> routeParams -> DataSource Throwable (Server.Response.Response data ErrorPage)
-        , action : Json.Decode.Value -> routeParams -> DataSource BuildError (Server.Response.Response action ErrorPage)
+        , action : Json.Decode.Value -> routeParams -> DataSource Throwable (Server.Response.Response action ErrorPage)
-        , staticRoutes : DataSource BuildError (List routeParams)
+        , staticRoutes : DataSource Throwable (List routeParams)
         , head :
             StaticPayload data action routeParams
             -> List Head.Tag
@@ -165,7 +165,7 @@ type Builder routeParams data action
             { moduleName : List String, routePattern : RoutePattern }
             -> (routeParams -> List ( String, String ))
             -> routeParams
-            -> DataSource BuildError (Maybe NotFoundReason)
+            -> DataSource Throwable (Maybe NotFoundReason)
         , kind : String
         }
 
@@ -292,14 +292,14 @@ buildWithSharedState config builderState =
 
 {-| -}
 single :
-    { data : DataSource BuildError data
+    { data : DataSource Throwable data
     , head : StaticPayload data action {} -> List Head.Tag
     }
     -> Builder {} data action
 single { data, head } =
     WithData
         { data = \_ _ -> data |> DataSource.map Server.Response.render
-        , action = \_ _ -> DataSource.fail (BuildError.internal "Internal Error - actions should never be called for statically generated pages.")
+        , action = \_ _ -> DataSource.fail (Exception.fromString "Internal Error - actions should never be called for statically generated pages.")
         , staticRoutes = DataSource.succeed [ {} ]
         , head = head
         , serverless = False
@@ -310,15 +310,15 @@ single { data, head } =
 
 {-| -}
 preRender :
-    { data : routeParams -> DataSource BuildError data
+    { data : routeParams -> DataSource Throwable data
-    , pages : DataSource BuildError (List routeParams)
+    , pages : DataSource Throwable (List routeParams)
     , head : StaticPayload data action routeParams -> List Head.Tag
     }
     -> Builder routeParams data action
 preRender { data, head, pages } =
     WithData
         { data = \_ -> data >> DataSource.map Server.Response.render
-        , action = \_ _ -> DataSource.fail (BuildError.internal "Internal Error - actions should never be called for statically generated pages.")
+        , action = \_ _ -> DataSource.fail (Exception.fromString "Internal Error - actions should never be called for statically generated pages.")
         , staticRoutes = pages
         , head = head
         , serverless = False
@@ -348,15 +348,15 @@ preRender { data, head, pages } =
 
 {-| -}
 preRenderWithFallback :
-    { data : routeParams -> DataSource BuildError (Server.Response.Response data ErrorPage)
+    { data : routeParams -> DataSource Throwable (Server.Response.Response data ErrorPage)
-    , pages : DataSource BuildError (List routeParams)
+    , pages : DataSource Throwable (List routeParams)
     , head : StaticPayload data action routeParams -> List Head.Tag
     }
     -> Builder routeParams data action
 preRenderWithFallback { data, head, pages } =
     WithData
         { data = \_ -> data
-        , action = \_ _ -> DataSource.fail (BuildError.internal "Internal Error - actions should never be called for statically generated pages.")
+        , action = \_ _ -> DataSource.fail (Exception.fromString "Internal Error - actions should never be called for statically generated pages.")
         , staticRoutes = pages
         , head = head
         , serverless = False
@@ -369,8 +369,8 @@ preRenderWithFallback { data, head, pages } =
 
 {-| -}
 serverRender :
-    { data : routeParams -> Server.Request.Parser (DataSource BuildError (Server.Response.Response data ErrorPage))
+    { data : routeParams -> Server.Request.Parser (DataSource Throwable (Server.Response.Response data ErrorPage))
-    , action : routeParams -> Server.Request.Parser (DataSource BuildError (Server.Response.Response action ErrorPage))
+    , action : routeParams -> Server.Request.Parser (DataSource Throwable (Server.Response.Response action ErrorPage))
     , head : StaticPayload data action routeParams -> List Head.Tag
     }
     -> Builder routeParams data action
@@ -396,7 +396,7 @@ serverRender { data, action, head } =
 
                                 Err error ->
                                     Server.Request.errorsToString error
-                                        |> BuildError.internal
+                                        |> Exception.fromString
                                         |> DataSource.fail
                         )
         , action =
@@ -419,7 +419,7 @@ serverRender { data, action, head } =
 
                                 Err error ->
                                     Server.Request.errorsToString error
-                                        |> BuildError.internal
+                                        |> Exception.fromString
                                         |> DataSource.fail
                         )
         , staticRoutes = DataSource.succeed []

generator/src/SharedTemplate.elm

@@ -1,8 +1,8 @@
 module SharedTemplate exposing (SharedTemplate)
 
-import BuildError exposing (BuildError)
 import DataSource
 import Effect exposing (Effect)
+import Exception exposing (Throwable)
 import Html exposing (Html)
 import Pages.Flags exposing (Flags)
 import Pages.PageUrl exposing (PageUrl)
@@ -36,7 +36,7 @@ type alias SharedTemplate msg sharedModel sharedData mappedMsg =
         -> (msg -> mappedMsg)
         -> View mappedMsg
         -> { body : List (Html mappedMsg), title : String }
-    , data : DataSource.DataSource BuildError sharedData
+    , data : DataSource.DataSource Throwable sharedData
     , subscriptions : Path -> sharedModel -> Sub msg
     , onPageChange :
         Maybe

generator/src/SiteConfig.elm

@@ -1,11 +1,11 @@
 module SiteConfig exposing (SiteConfig)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 
 
 type alias SiteConfig =
     { canonicalUrl : String
-    , head : DataSource BuildError (List Head.Tag)
+    , head : DataSource Throwable (List Head.Tag)
     }

plugins/MarkdownCodec.elm

@@ -1,8 +1,8 @@
 module MarkdownCodec exposing (isPlaceholder, noteTitle, titleAndDescription, withFrontmatter, withoutFrontmatter)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.File as StaticFile
+import Exception exposing (Throwable)
 import Json.Decode as Decode exposing (Decoder)
 import Json.Decode.Extra
 import List.Extra
@@ -12,15 +12,15 @@ import Markdown.Renderer
 import MarkdownExtra
 
 
-isPlaceholder : String -> DataSource BuildError (Maybe ())
+isPlaceholder : String -> DataSource Throwable (Maybe ())
 isPlaceholder filePath =
     filePath
         |> StaticFile.bodyWithoutFrontmatter
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
         |> DataSource.andThen
             (\rawContent ->
                 Markdown.Parser.parse rawContent
-                    |> Result.mapError (\_ -> BuildError.internal "Markdown error")
+                    |> Result.mapError (\_ -> Exception.fromString "Markdown error")
                     |> Result.map
                         (\blocks ->
                             List.any
@@ -47,7 +47,7 @@ isPlaceholder filePath =
             )
 
 
-noteTitle : String -> DataSource BuildError String
+noteTitle : String -> DataSource Throwable String
 noteTitle filePath =
     titleFromFrontmatter filePath
         |> DataSource.andThen
@@ -56,7 +56,7 @@ noteTitle filePath =
                     |> Maybe.map DataSource.succeed
                     |> Maybe.withDefault
                         (StaticFile.bodyWithoutFrontmatter filePath
-                            |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                            |> DataSource.throw
                             |> DataSource.andThen
                                 (\rawContent ->
                                     Markdown.Parser.parse rawContent
@@ -76,13 +76,13 @@ noteTitle filePath =
                                             )
                                         |> Result.andThen (Result.fromMaybe <| "Expected to find an H1 heading for page " ++ filePath)
                                         |> DataSource.fromResult
-                                        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                                        |> DataSource.throw
                                 )
                         )
             )
 
 
-titleAndDescription : String -> DataSource BuildError { title : String, description : String }
+titleAndDescription : String -> DataSource Throwable { title : String, description : String }
 titleAndDescription filePath =
     filePath
         |> StaticFile.onlyFrontmatter
@@ -90,7 +90,7 @@ titleAndDescription filePath =
                 (Json.Decode.Extra.optionalField "title" Decode.string)
                 (Json.Decode.Extra.optionalField "description" Decode.string)
             )
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
         |> DataSource.andThen
             (\metadata ->
                 Maybe.map2 (\title description -> { title = title, description = description })
@@ -99,7 +99,7 @@ titleAndDescription filePath =
                     |> Maybe.map DataSource.succeed
                     |> Maybe.withDefault
                         (StaticFile.bodyWithoutFrontmatter filePath
-                            |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                            |> DataSource.throw
                             |> DataSource.andThen
                                 (\rawContent ->
                                     Markdown.Parser.parse rawContent
@@ -127,8 +127,8 @@ titleAndDescription filePath =
                                                     )
                                             )
                                         |> Result.andThen (Result.fromMaybe <| "Expected to find an H1 heading for page " ++ filePath)
+                                        |> Result.mapError Exception.fromString
                                         |> DataSource.fromResult
-                                        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
                                 )
                         )
             )
@@ -163,27 +163,27 @@ findDescription blocks =
         |> Maybe.withDefault ""
 
 
-titleFromFrontmatter : String -> DataSource BuildError (Maybe String)
+titleFromFrontmatter : String -> DataSource Throwable (Maybe String)
 titleFromFrontmatter filePath =
     StaticFile.onlyFrontmatter
         (Json.Decode.Extra.optionalField "title" Decode.string)
         filePath
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
 
 
 withoutFrontmatter :
     Markdown.Renderer.Renderer view
     -> String
-    -> DataSource BuildError (List Block)
+    -> DataSource Throwable (List Block)
 withoutFrontmatter renderer filePath =
     (filePath
         |> StaticFile.bodyWithoutFrontmatter
-        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+        |> DataSource.throw
         |> DataSource.andThen
             (\rawBody ->
                 rawBody
                     |> Markdown.Parser.parse
-                    |> Result.mapError (\_ -> BuildError.internal "Couldn't parse markdown.")
+                    |> Result.mapError (\_ -> Exception.fromString "Couldn't parse markdown.")
                     |> DataSource.fromResult
             )
     )
@@ -195,7 +195,7 @@ withoutFrontmatter renderer filePath =
                     -- but we can at least make sure there are no errors turning it into HTML before encoding it
                     |> Result.map (\_ -> blocks)
                     |> DataSource.fromResult
-                    |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                    |> DataSource.throw
             )
 
 
@@ -204,22 +204,22 @@ withFrontmatter :
     -> Decoder frontmatter
     -> Markdown.Renderer.Renderer view
     -> String
-    -> DataSource BuildError value
+    -> DataSource Throwable value
 withFrontmatter constructor frontmatterDecoder_ renderer filePath =
     DataSource.map2 constructor
         (StaticFile.onlyFrontmatter
             frontmatterDecoder_
             filePath
-            |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+            |> DataSource.throw
         )
         (StaticFile.bodyWithoutFrontmatter
             filePath
-            |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+            |> DataSource.throw
             |> DataSource.andThen
                 (\rawBody ->
                     rawBody
                         |> Markdown.Parser.parse
-                        |> Result.mapError (\_ -> BuildError.internal "Couldn't parse markdown.")
+                        |> Result.mapError (\_ -> Exception.fromString "Couldn't parse markdown.")
                         |> DataSource.fromResult
                 )
             |> DataSource.andThen
@@ -230,6 +230,6 @@ withFrontmatter constructor frontmatterDecoder_ renderer filePath =
                         -- but we can at least make sure there are no errors turning it into HTML before encoding it
                         |> Result.map (\_ -> blocks)
                         |> DataSource.fromResult
-                        |> DataSource.onError (\_ -> DataSource.fail (BuildError.internal "TODO map to more informative error"))
+                        |> DataSource.throw
                 )
         )

src/ApiRoute.elm

@@ -172,8 +172,8 @@ You define your ApiRoute's in `app/Api.elm`. Here's a simple example:
 
 -}
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Internal.ApiRoute exposing (ApiRoute(..), ApiRouteBuilder(..))
 import Json.Decode as Decode
@@ -192,7 +192,7 @@ type alias ApiRoute response =
 {-| Same as [`preRender`](#preRender), but for an ApiRoute that has no dynamic segments. This is just a bit simpler because
 since there are no dynamic segments, you don't need to provide a DataSource with the list of dynamic segments to pre-render because there is only a single possible route.
 -}
-single : ApiRouteBuilder (DataSource BuildError String) (List String) -> ApiRoute Response
+single : ApiRouteBuilder (DataSource Throwable String) (List String) -> ApiRoute Response
 single handler =
     handler
         |> preRender (\constructor -> DataSource.succeed [ constructor ])
@@ -259,10 +259,10 @@ serverRender ((ApiRouteBuilder patterns pattern _ _ _) as fullHandler) =
 
 
 {-| -}
-preRenderWithFallback : (constructor -> DataSource BuildError (List (List String))) -> ApiRouteBuilder (DataSource BuildError (Server.Response.Response Never Never)) constructor -> ApiRoute Response
+preRenderWithFallback : (constructor -> DataSource Throwable (List (List String))) -> ApiRouteBuilder (DataSource Throwable (Server.Response.Response Never Never)) constructor -> ApiRoute Response
 preRenderWithFallback buildUrls ((ApiRouteBuilder patterns pattern _ toString constructor) as fullHandler) =
     let
-        buildTimeRoutes__ : DataSource BuildError (List String)
+        buildTimeRoutes__ : DataSource Throwable (List String)
         buildTimeRoutes__ =
             buildUrls (constructor [])
                 |> DataSource.map (List.map toString)
@@ -301,15 +301,15 @@ encodeStaticFileBody fileBody =
 
 
 {-| -}
-preRender : (constructor -> DataSource BuildError (List (List String))) -> ApiRouteBuilder (DataSource BuildError String) constructor -> ApiRoute Response
+preRender : (constructor -> DataSource Throwable (List (List String))) -> ApiRouteBuilder (DataSource Throwable String) constructor -> ApiRoute Response
 preRender buildUrls ((ApiRouteBuilder patterns pattern _ toString constructor) as fullHandler) =
     let
-        buildTimeRoutes__ : DataSource BuildError (List String)
+        buildTimeRoutes__ : DataSource Throwable (List String)
         buildTimeRoutes__ =
             buildUrls (constructor [])
                 |> DataSource.map (List.map toString)
 
-        preBuiltMatches : DataSource BuildError (List (List String))
+        preBuiltMatches : DataSource Throwable (List (List String))
         preBuiltMatches =
             buildUrls (constructor [])
     in
@@ -322,7 +322,7 @@ preRender buildUrls ((ApiRouteBuilder patterns pattern _ toString constructor) a
                     matches =
                         Internal.ApiRoute.pathToMatches path fullHandler
 
-                    routeFound : DataSource BuildError Bool
+                    routeFound : DataSource Throwable Bool
                     routeFound =
                         preBuiltMatches
                             |> DataSource.map (List.member matches)
@@ -431,20 +431,20 @@ capture (ApiRouteBuilder patterns pattern previousHandler toString constructor)
 
 {-| For internal use by generated code. Not so useful in user-land.
 -}
-getBuildTimeRoutes : ApiRoute response -> DataSource BuildError (List String)
+getBuildTimeRoutes : ApiRoute response -> DataSource Throwable (List String)
 getBuildTimeRoutes (ApiRoute handler) =
     handler.buildTimeRoutes
 
 
 {-| Include head tags on every page's HTML.
 -}
-withGlobalHeadTags : DataSource BuildError (List Head.Tag) -> ApiRoute response -> ApiRoute response
+withGlobalHeadTags : DataSource Throwable (List Head.Tag) -> ApiRoute response -> ApiRoute response
 withGlobalHeadTags globalHeadTags (ApiRoute handler) =
     ApiRoute { handler | globalHeadTags = Just globalHeadTags }
 
 
 {-| -}
-getGlobalHeadTagsDataSource : ApiRoute response -> Maybe (DataSource BuildError (List Head.Tag))
+getGlobalHeadTagsDataSource : ApiRoute response -> Maybe (DataSource Throwable (List Head.Tag))
 getGlobalHeadTagsDataSource (ApiRoute handler) =
     handler.globalHeadTags
 

src/DataSource.elm

@@ -5,7 +5,7 @@ module DataSource exposing
     , andThen, resolve, combine
     , andMap
     , map2, map3, map4, map5, map6, map7, map8, map9
-    , mapError, onError
+    , catch, mapError, onError, throw
     )
 
 {-| In an `elm-pages` app, each Route Module can define a value `data` which is a `DataSource` that will be resolved **before** `init` is called. That means it is also available
@@ -82,6 +82,7 @@ Any place in your `elm-pages` app where the framework lets you pass in a value o
 -}
 
 import Dict
+import Exception exposing (Catchable(..), Throwable)
 import Pages.StaticHttpRequest exposing (RawRequest(..))
 
 
@@ -524,3 +525,20 @@ map9 combineFn request1 request2 request3 request4 request5 request6 request7 re
         |> map2 (|>) request7
         |> map2 (|>) request8
         |> map2 (|>) request9
+
+
+catch : DataSource (Catchable error) value -> DataSource error value
+catch ds =
+    ds
+        |> onError
+            (\exception ->
+                case exception of
+                    Catchable error string ->
+                        fail error
+            )
+
+
+throw : DataSource (Catchable error) data -> DataSource Throwable data
+throw dataSource =
+    dataSource
+        |> onError (Exception.throw >> fail)

src/DataSource/Env.elm

@@ -35,6 +35,7 @@ import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.Http
 import DataSource.Internal.Request
+import Exception exposing (Catchable)
 import Json.Decode as Decode
 import Json.Encode as Encode
 
@@ -64,7 +65,7 @@ toBuildError (MissingEnvVariable errorName) =
 
 {-| Get an environment variable, or a DataSource failure if there is no environment variable matching that name.
 -}
-expect : String -> DataSource Error String
+expect : String -> DataSource (Catchable Error) String
 expect envVariableName =
     envVariableName
         |> get
@@ -73,5 +74,5 @@ expect envVariableName =
                 maybeValue
                     |> Result.fromMaybe ("DataSource.Env.expect was expecting a variable `" ++ envVariableName ++ "` but couldn't find a variable with that name.")
                     |> DataSource.fromResult
-                    |> DataSource.onError (\_ -> DataSource.fail (MissingEnvVariable envVariableName))
+                    |> DataSource.onError (\_ -> DataSource.fail (Exception.Catchable (MissingEnvVariable envVariableName) "TODO"))
             )

src/DataSource/File.elm

@@ -47,6 +47,7 @@ import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import DataSource.Http
 import DataSource.Internal.Request
+import Exception exposing (Catchable, Throwable)
 import Json.Decode as Decode exposing (Decoder)
 
 
@@ -135,7 +136,7 @@ It's common to parse the body with a markdown parser or other format.
                 )
 
 -}
-bodyWithFrontmatter : (String -> Decoder frontmatter) -> String -> DataSource (FileReadError Decode.Error) frontmatter
+bodyWithFrontmatter : (String -> Decoder frontmatter) -> String -> DataSource (Catchable (FileReadError Decode.Error)) frontmatter
 bodyWithFrontmatter frontmatterDecoder filePath =
     read filePath
         (body
@@ -206,7 +207,7 @@ the [`DataSource`](DataSource) API along with [`DataSource.Glob`](DataSource-Glo
             |> DataSource.resolve
 
 -}
-onlyFrontmatter : Decoder frontmatter -> String -> DataSource (FileReadError Decode.Error) frontmatter
+onlyFrontmatter : Decoder frontmatter -> String -> DataSource (Catchable (FileReadError Decode.Error)) frontmatter
 onlyFrontmatter frontmatterDecoder filePath =
     read filePath
         (frontmatter frontmatterDecoder)
@@ -233,7 +234,7 @@ Hey there! This is my first post :)
 Then data will yield the value `"Hey there! This is my first post :)"`.
 
 -}
-bodyWithoutFrontmatter : String -> DataSource (FileReadError decoderError) String
+bodyWithoutFrontmatter : String -> DataSource (Catchable (FileReadError decoderError)) String
 bodyWithoutFrontmatter filePath =
     read filePath
         body
@@ -257,7 +258,7 @@ You could read a file called `hello.txt` in your root project directory like thi
         File.rawFile "hello.txt"
 
 -}
-rawFile : String -> DataSource (FileReadError decoderError) String
+rawFile : String -> DataSource (Catchable (FileReadError decoderError)) String
 rawFile filePath =
     read filePath (Decode.field "rawFile" Decode.string)
 
@@ -285,7 +286,7 @@ The Decode will strip off any unused JSON data.
             "elm.json"
 
 -}
-jsonFile : Decoder a -> String -> DataSource (FileReadError Decode.Error) a
+jsonFile : Decoder a -> String -> DataSource (Catchable (FileReadError Decode.Error)) a
 jsonFile jsonFileDecoder filePath =
     rawFile filePath
         |> DataSource.onError (\foo -> Debug.todo "TODO: Not handled yet")
@@ -294,8 +295,8 @@ jsonFile jsonFileDecoder filePath =
                 jsonString
                     |> Decode.decodeString jsonFileDecoder
                     |> Result.mapError DecodingError
-                    --|> Result.mapError Decode.errorToString
                     |> DataSource.fromResult
+                    |> DataSource.onError (\error -> DataSource.fail <| Exception.Catchable error "TODO error message here")
             )
 
 
@@ -306,7 +307,7 @@ body =
     Decode.field "withoutFrontmatter" Decode.string
 
 
-read : String -> Decoder a -> DataSource (FileReadError error) a
+read : String -> Decoder a -> DataSource (Catchable (FileReadError error)) a
 read filePath decoder =
     DataSource.Internal.Request.request
         { name = "read-file"
@@ -321,6 +322,7 @@ read filePath decoder =
         }
         |> DataSource.onError (\_ -> Debug.todo "TODO: not handled")
         |> DataSource.andThen DataSource.fromResult
+        |> DataSource.onError (\error -> DataSource.fail <| Exception.Catchable error "TODO error message here")
 
 
 errorDecoder : Decoder (FileReadError decoding)

src/DataSource/Glob.elm

@@ -229,6 +229,7 @@ import DataSource exposing (DataSource)
 import DataSource.Http
 import DataSource.Internal.Glob exposing (Glob(..))
 import DataSource.Internal.Request
+import Exception exposing (Catchable, Throwable)
 import Json.Decode as Decode
 import Json.Encode as Encode
 import List.Extra
@@ -1053,7 +1054,7 @@ so it's ideal to make this kind of assertion rather than having fallback behavio
 issues (like if we had instead ignored the case where there are two or more matching blog post files).
 
 -}
-expectUniqueMatch : Glob a -> DataSource String a
+expectUniqueMatch : Glob a -> DataSource (Catchable String) a
 expectUniqueMatch glob =
     glob
         |> toDataSource
@@ -1064,10 +1065,16 @@ expectUniqueMatch glob =
                         DataSource.succeed file
 
                     [] ->
-                        DataSource.fail <| "No files matched the pattern: " ++ toPatternString glob
+                        DataSource.fail <|
+                            Exception.fromStringWithValue
+                                ("No files matched the pattern: " ++ toPatternString glob)
+                                ("No files matched the pattern: " ++ toPatternString glob)
 
                     _ ->
-                        DataSource.fail "More than one file matched."
+                        DataSource.fail <|
+                            Exception.fromStringWithValue
+                                "More than one file matched."
+                                "More than one file matched."
             )
 
 

src/DataSource/Http.elm

@@ -70,6 +70,7 @@ import Bytes exposing (Bytes)
 import Bytes.Decode
 import DataSource exposing (DataSource)
 import Dict exposing (Dict)
+import Exception exposing (Catchable)
 import Json.Decode
 import Json.Encode as Encode
 import Pages.Internal.StaticHttpBody as Body
@@ -126,7 +127,7 @@ type alias Body =
 get :
     String
     -> Json.Decode.Decoder a
-    -> DataSource Pages.StaticHttpRequest.Error a
+    -> DataSource (Catchable Pages.StaticHttpRequest.Error) a
 get url decoder =
     request
         ((\okUrl ->
@@ -253,7 +254,7 @@ expectToString expect =
 request :
     RequestDetails
     -> Expect a
-    -> DataSource Pages.StaticHttpRequest.Error a
+    -> DataSource (Catchable Pages.StaticHttpRequest.Error) a
 request request__ expect =
     let
         request_ : HashRequest.Request
@@ -272,7 +273,7 @@ request request__ expect =
 uncachedRequest :
     RequestDetails
     -> Expect a
-    -> DataSource Pages.StaticHttpRequest.Error a
+    -> DataSource (Catchable Pages.StaticHttpRequest.Error) a
 uncachedRequest request__ expect =
     let
         request_ : HashRequest.Request
@@ -294,7 +295,7 @@ with this as a low-level detail, or you can use functions like [DataSource.Http.
 requestRaw :
     HashRequest.Request
     -> Expect a
-    -> DataSource Pages.StaticHttpRequest.Error a
+    -> DataSource (Catchable Pages.StaticHttpRequest.Error) a
 requestRaw request__ expect =
     let
         request_ : HashRequest.Request
@@ -406,6 +407,7 @@ requestRaw request__ expect =
                                     )
                     )
                 |> toResult
+                |> DataSource.mapError (\error -> Exception.Catchable error "TODO - error message here")
         )
 
 

src/Exception.elm

@@ -0,0 +1,26 @@
+module Exception exposing (Catchable(..), Throwable, fromString, fromStringWithValue, throw)
+
+
+type alias Throwable =
+    Catchable ()
+
+
+type Catchable error
+    = Catchable error String
+
+
+fromString : String -> Catchable ()
+fromString string =
+    Catchable () string
+
+
+fromStringWithValue : String -> value -> Catchable value
+fromStringWithValue string value =
+    Catchable value string
+
+
+throw : Catchable error -> Catchable ()
+throw exception =
+    case exception of
+        Catchable error string ->
+            Catchable () string

src/Internal/ApiRoute.elm

@@ -8,8 +8,8 @@ module Internal.ApiRoute exposing
     , withRoutes
     )
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 import Json.Decode
 import Pattern exposing (Pattern)
@@ -46,12 +46,12 @@ tryMatchDone path (ApiRoute handler) =
 type ApiRoute response
     = ApiRoute
         { regex : Regex
-        , matchesToResponse : Json.Decode.Value -> String -> DataSource BuildError (Maybe response)
+        , matchesToResponse : Json.Decode.Value -> String -> DataSource Throwable (Maybe response)
-        , buildTimeRoutes : DataSource BuildError (List String)
+        , buildTimeRoutes : DataSource Throwable (List String)
-        , handleRoute : String -> DataSource BuildError Bool
+        , handleRoute : String -> DataSource Throwable Bool
         , pattern : Pattern
         , kind : String
-        , globalHeadTags : Maybe (DataSource BuildError (List Head.Tag))
+        , globalHeadTags : Maybe (DataSource Throwable (List Head.Tag))
         }
 
 

src/Pages/Internal/Platform/Cli.elm

@@ -12,6 +12,7 @@ import Bytes.Encode
 import Codec
 import DataSource exposing (DataSource)
 import Dict
+import Exception exposing (Throwable)
 import Head exposing (Tag)
 import Html exposing (Html)
 import HtmlPrinter
@@ -50,7 +51,7 @@ currentCompatibilityKey =
 
 {-| -}
 type alias Model route =
-    { staticResponses : DataSource BuildError Effect
+    { staticResponses : DataSource Throwable Effect
     , errors : List BuildError
     , allRawResponses : RequestsAndPending
     , maybeRequestJson : RenderRequest route
@@ -414,11 +415,11 @@ initLegacy :
     -> ( Model route, Effect )
 initLegacy site ((RenderRequest.SinglePage includeHtml singleRequest _) as renderRequest) { isDevServer } config =
     let
-        globalHeadTags : DataSource BuildError (List Tag)
+        globalHeadTags : DataSource Throwable (List Tag)
         globalHeadTags =
             (config.globalHeadTags |> Maybe.withDefault (\_ -> DataSource.succeed [])) HtmlPrinter.htmlToString
 
-        staticResponsesNew : DataSource BuildError Effect
+        staticResponsesNew : DataSource Throwable Effect
         staticResponsesNew =
             StaticResponses.renderApiRequest
                 (case singleRequest of

src/Pages/Internal/Platform/StaticResponses.elm

@@ -3,20 +3,21 @@ module Pages.Internal.Platform.StaticResponses exposing (NextStep(..), batchUpda
 import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
 import Dict
+import Exception exposing (Catchable(..), Throwable)
 import List.Extra
 import Pages.StaticHttp.Request as HashRequest
 import Pages.StaticHttpRequest as StaticHttpRequest
 import RequestsAndPending exposing (RequestsAndPending)
 
 
-empty : a -> DataSource BuildError a
+empty : a -> DataSource Throwable a
 empty a =
     DataSource.succeed a
 
 
 renderApiRequest :
-    DataSource BuildError response
+    DataSource Throwable response
-    -> DataSource BuildError response
+    -> DataSource Throwable response
 renderApiRequest request =
     request
 
@@ -49,21 +50,21 @@ batchUpdate newEntries model =
 
 
 type NextStep route value
-    = Continue (List HashRequest.Request) (StaticHttpRequest.RawRequest BuildError value)
+    = Continue (List HashRequest.Request) (StaticHttpRequest.RawRequest Throwable value)
     | Finish value
     | FinishedWithErrors (List BuildError)
 
 
 nextStep :
     { model
-        | staticResponses : DataSource BuildError a
+        | staticResponses : DataSource Throwable a
         , errors : List BuildError
         , allRawResponses : RequestsAndPending
     }
     -> NextStep route a
 nextStep ({ allRawResponses, errors } as model) =
     let
-        staticRequestsStatus : StaticHttpRequest.Status BuildError a
+        staticRequestsStatus : StaticHttpRequest.Status Throwable a
         staticRequestsStatus =
             allRawResponses
                 |> StaticHttpRequest.cacheRequestResolution model.staticResponses
@@ -88,7 +89,7 @@ nextStep ({ allRawResponses, errors } as model) =
                 StaticHttpRequest.HasPermanentError _ ->
                     ( ( False, Nothing )
                     , []
-                    , DataSource.fail (BuildError.internal "TODO this shouldn't happen")
+                    , DataSource.fail (Exception.fromString "TODO this shouldn't happen")
                     )
     in
     if pendingRequests then
@@ -136,9 +137,9 @@ nextStep ({ allRawResponses, errors } as model) =
                 Just (Ok completed) ->
                     Finish completed
 
-                Just (Err buildError) ->
+                Just (Err (Catchable () buildError)) ->
                     FinishedWithErrors
-                        [ buildError
+                        [ buildError |> BuildError.internal
                         ]
 
                 Nothing ->

src/Pages/Manifest.elm

@@ -64,11 +64,11 @@ You pass your `Pages.Manifest.Config` record into the `Pages.application` functi
 -}
 
 import ApiRoute
-import BuildError exposing (BuildError)
 import Color exposing (Color)
 import Color.Convert
 import DataSource exposing (DataSource)
 import Dict exposing (Dict)
+import Exception exposing (Throwable)
 import Head
 import Json.Encode as Encode
 import LanguageTag exposing (LanguageTag, emptySubtags)
@@ -345,7 +345,7 @@ nonEmptyList list =
 
 {-| A generator for Api.elm to include a manifest.json.
 -}
-generator : String -> DataSource BuildError Config -> ApiRoute.ApiRoute ApiRoute.Response
+generator : String -> DataSource Throwable Config -> ApiRoute.ApiRoute ApiRoute.Response
 generator canonicalSiteUrl config =
     ApiRoute.succeed
         (config

src/Pages/ProgramConfig.elm

@@ -2,12 +2,12 @@ module Pages.ProgramConfig exposing (ProgramConfig)
 
 import ApiRoute
 import Browser.Navigation
-import BuildError exposing (BuildError)
 import Bytes exposing (Bytes)
 import Bytes.Decode
 import Bytes.Encode
 import DataSource exposing (DataSource)
 import Dict exposing (Dict)
+import Exception exposing (Throwable)
 import Form.FormData exposing (FormData)
 import Head
 import Html exposing (Html)
@@ -49,9 +49,9 @@ type alias ProgramConfig userMsg userModel route pageData actionData sharedData
         -> ( userModel, effect )
     , update : Pages.FormState.PageFormState -> Dict String (Pages.Transition.FetcherState actionData) -> Maybe Pages.Transition.Transition -> sharedData -> pageData -> Maybe Browser.Navigation.Key -> userMsg -> userModel -> ( userModel, effect )
     , subscriptions : route -> Path -> userModel -> Sub userMsg
-    , sharedData : DataSource BuildError sharedData
+    , sharedData : DataSource Throwable sharedData
-    , data : Decode.Value -> route -> DataSource BuildError (PageServerResponse pageData errorPage)
+    , data : Decode.Value -> route -> DataSource Throwable (PageServerResponse pageData errorPage)
-    , action : Decode.Value -> route -> DataSource BuildError (PageServerResponse actionData errorPage)
+    , action : Decode.Value -> route -> DataSource Throwable (PageServerResponse actionData errorPage)
     , onActionData : actionData -> Maybe userMsg
     , view :
         Pages.FormState.PageFormState
@@ -69,8 +69,8 @@ type alias ProgramConfig userMsg userModel route pageData actionData sharedData
             { view : userModel -> { title : String, body : List (Html (Pages.Msg.Msg userMsg)) }
             , head : List Head.Tag
             }
-    , handleRoute : route -> DataSource BuildError (Maybe NotFoundReason)
+    , handleRoute : route -> DataSource Throwable (Maybe NotFoundReason)
-    , getStaticRoutes : DataSource BuildError (List route)
+    , getStaticRoutes : DataSource Throwable (List route)
     , urlToRoute : Url -> route
     , routeToPath : route -> List String
     , site : Maybe SiteConfig
@@ -102,7 +102,7 @@ type alias ProgramConfig userMsg userModel route pageData actionData sharedData
     , encodeResponse : ResponseSketch pageData actionData sharedData -> Bytes.Encode.Encoder
     , encodeAction : actionData -> Bytes.Encode.Encoder
     , decodeResponse : Bytes.Decode.Decoder (ResponseSketch pageData actionData sharedData)
-    , globalHeadTags : Maybe ((Maybe { indent : Int, newLines : Bool } -> Html Never -> String) -> DataSource BuildError (List Head.Tag))
+    , globalHeadTags : Maybe ((Maybe { indent : Int, newLines : Bool } -> Html Never -> String) -> DataSource Throwable (List Head.Tag))
     , cmdToEffect : Cmd userMsg -> effect
     , perform :
         { fetchRouteData :

src/Pages/SiteConfig.elm

@@ -1,11 +1,11 @@
 module Pages.SiteConfig exposing (SiteConfig)
 
-import BuildError exposing (BuildError)
 import DataSource exposing (DataSource)
+import Exception exposing (Throwable)
 import Head
 
 
 type alias SiteConfig =
     { canonicalUrl : String
-    , head : DataSource BuildError (List Head.Tag)
+    , head : DataSource Throwable (List Head.Tag)
     }