Include inlined source maps when compiling projects. The actual source map generation is not done.

builder/src/Generate.hs

@@ -37,7 +37,7 @@ import Prelude hiding (cycle, print)
 type Task a =
   Task.Task Exit.Generate a
 
-debug :: FilePath -> Details.Details -> Build.Artifacts -> Task B.Builder
+debug :: FilePath -> Details.Details -> Build.Artifacts -> Task JS.GeneratedResult
 debug root details (Build.Artifacts pkg ifaces roots modules) =
   do
     loading <- loadObjects root details modules
@@ -46,20 +46,18 @@ debug root details (Build.Artifacts pkg ifaces roots modules) =
     let mode = Mode.Dev (Just types)
     let graph = objectsToGlobalGraph objects
     let mains = gatherMains pkg objects roots
-    let (JS.GeneratedResult state) = JS.generate mode graph mains
-    return state
+    return $ JS.generate mode graph mains
 
-dev :: FilePath -> Details.Details -> Build.Artifacts -> Task B.Builder
+dev :: FilePath -> Details.Details -> Build.Artifacts -> Task JS.GeneratedResult
 dev root details (Build.Artifacts pkg _ roots modules) =
   do
     objects <- finalizeObjects =<< loadObjects root details modules
     let mode = Mode.Dev Nothing
     let graph = objectsToGlobalGraph objects
     let mains = gatherMains pkg objects roots
-    let (JS.GeneratedResult state) = JS.generate mode graph mains
-    return state
+    return $ JS.generate mode graph mains
 
-prod :: FilePath -> Details.Details -> Build.Artifacts -> Task B.Builder
+prod :: FilePath -> Details.Details -> Build.Artifacts -> Task JS.GeneratedResult
 prod root details (Build.Artifacts pkg _ roots modules) =
   do
     objects <- finalizeObjects =<< loadObjects root details modules
@@ -67,8 +65,7 @@ prod root details (Build.Artifacts pkg _ roots modules) =
     let graph = objectsToGlobalGraph objects
     let mode = Mode.Prod (Mode.shortenFieldNames graph)
     let mains = gatherMains pkg objects roots
-    let (JS.GeneratedResult state) = JS.generate mode graph mains
-    return state
+    return $ JS.generate mode graph mains
 
 repl :: FilePath -> Details.Details -> Bool -> Build.ReplArtifacts -> N.Name -> Task B.Builder
 repl root details ansi (Build.ReplArtifacts home modules localizer annotations) name =

compiler/src/Generate/JavaScript.hs

@@ -23,6 +23,7 @@ import Generate.JavaScript.Expression qualified as Expr
 import Generate.JavaScript.Functions qualified as Functions
 import Generate.JavaScript.Name qualified as JsName
 import Generate.Mode qualified as Mode
+import Generate.SourceMap qualified as SourceMap
 import Gren.Kernel qualified as K
 import Gren.ModuleName qualified as ModuleName
 import Reporting.Doc qualified as D
@@ -36,8 +37,10 @@ type Graph = Map.Map Opt.Global Opt.Node
 
 type Mains = Map.Map ModuleName.Canonical Opt.Main
 
-newtype GeneratedResult = GeneratedResult
-  {_source :: B.Builder}
+data GeneratedResult = GeneratedResult
+  { _source :: B.Builder,
+    _sourceMap :: SourceMap.SourceMap
+  }
 
 prelude :: B.Builder
 prelude =
@@ -56,7 +59,11 @@ generate mode (Opt.GlobalGraph graph _) mains =
           <> stateToBuilder state
           <> toMainExports mode mains
           <> "}(this.module ? this.module.exports : this));"
-   in GeneratedResult {_source = builder}
+      sourceMap = SourceMap.generate $ stateToMappings state
+   in GeneratedResult
+        { _source = builder,
+          _sourceMap = sourceMap
+        }
 
 addMain :: Mode.Mode -> Graph -> ModuleName.Canonical -> Opt.Main -> State -> State
 addMain mode graph home _ state =
@@ -114,6 +121,10 @@ stateToBuilder :: State -> B.Builder
 stateToBuilder (State _ builder) =
   JS._code builder
 
+stateToMappings :: State -> [JS.Mapping]
+stateToMappings (State _ builder) =
+  JS._mappings builder
+
 -- ADD DEPENDENCIES
 
 addGlobal :: Mode.Mode -> Graph -> State -> Opt.Global -> State

compiler/src/Generate/JavaScript/Builder.hs

@@ -3,6 +3,7 @@
 
 module Generate.JavaScript.Builder
   ( Builder (..),
+    Mapping (..),
     emptyBuilder,
     stmtToBuilder,
     exprToBuilder,

compiler/src/Generate/SourceMap.hs

@@ -0,0 +1,22 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Generate.SourceMap (SourceMap, generate, sandwhich, toBytes) where
+
+import Data.ByteString.Builder qualified as B
+import Generate.JavaScript.Builder qualified as JS
+
+newtype SourceMap = SourceMap B.Builder
+
+generate :: [JS.Mapping] -> SourceMap
+generate _ = SourceMap $ B.char7 '\0'
+
+sandwhich :: SourceMap -> B.Builder -> B.Builder
+sandwhich (SourceMap mapBytes) sourceBytes =
+  sourceBytes
+    <> "\n"
+    <> "//# sourceMappingURL=data:application/json;base64,"
+    <> mapBytes
+
+toBytes :: SourceMap -> B.Builder
+toBytes (SourceMap bytes) =
+  bytes

gren.cabal

@@ -152,6 +152,7 @@ Common gren-common
         Generate.JavaScript.Functions
         Generate.JavaScript.Name
         Generate.Mode
+        Generate.SourceMap
         Nitpick.Debug
         Nitpick.PatternMatches
         Optimize.Case

terminal/src/Make.hs

@@ -20,7 +20,9 @@ import Directories qualified as Dirs
 import File qualified
 import Generate qualified
 import Generate.Html qualified as Html
+import Generate.JavaScript qualified as JS
 import Generate.Node qualified as Node
+import Generate.SourceMap qualified as SourceMap
 import Gren.Details qualified as Details
 import Gren.ModuleName qualified as ModuleName
 import Gren.Platform qualified as Platform
@@ -64,7 +66,7 @@ run paths flags@(Flags _ _ maybeOutput report) =
     Reporting.attemptWithStyle style Exit.makeToReport $
       case maybeRoot of
         Just root -> runHelp root paths style flags
-        Nothing -> return $ Left $ Exit.MakeNoOutline
+        Nothing -> return $ Left Exit.MakeNoOutline
 
 runHelp :: FilePath -> [FilePath] -> Reporting.Style -> Flags -> IO (Either Exit.Make ())
 runHelp root paths style (Flags debug optimize maybeOutput _) =
@@ -100,47 +102,47 @@ runHelp root paths style (Flags debug optimize maybeOutput _) =
                                 return ()
                               (Platform.Browser, [name]) ->
                                 do
-                                  builder <- toBuilder root details desiredMode artifacts
-                                  generate style "index.html" (Html.sandwich name builder) (NE.List name [])
+                                  (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                  writeToDisk style "index.html" (Html.sandwich name (SourceMap.sandwhich sourceMap source)) (NE.List name [])
                               (Platform.Node, [name]) ->
                                 do
-                                  builder <- toBuilder root details desiredMode artifacts
-                                  generate style "app" (Node.sandwich name builder) (NE.List name [])
+                                  (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                  writeToDisk style "app" (SourceMap.sandwhich sourceMap (Node.sandwich name source)) (NE.List name [])
                               (_, name : names) ->
                                 do
-                                  builder <- toBuilder root details desiredMode artifacts
-                                  generate style "index.js" builder (NE.List name names)
+                                  (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                  writeToDisk style "index.js" (SourceMap.sandwhich sourceMap source) (NE.List name names)
                           Just DevStdOut ->
                             case getMains artifacts of
                               [] ->
                                 return ()
                               _ ->
                                 do
-                                  builder <- toBuilder root details desiredMode artifacts
-                                  Task.io $ B.hPutBuilder IO.stdout builder
+                                  (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                  Task.io $ B.hPutBuilder IO.stdout (SourceMap.sandwhich sourceMap source)
                           Just DevNull ->
                             return ()
                           Just (Exe target) ->
                             case platform of
                               Platform.Node -> do
                                 name <- hasOneMain artifacts
-                                builder <- toBuilder root details desiredMode artifacts
-                                generate style target (Node.sandwich name builder) (NE.List name [])
+                                (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                writeToDisk style target (SourceMap.sandwhich sourceMap (Node.sandwich name source)) (NE.List name [])
                               _ -> do
                                 Task.throw Exit.MakeExeOnlyForNodePlatform
                           Just (JS target) ->
                             case getNoMains artifacts of
                               [] -> do
-                                builder <- toBuilder root details desiredMode artifacts
-                                generate style target builder (Build.getRootNames artifacts)
+                                (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                writeToDisk style target (SourceMap.sandwhich sourceMap source) (Build.getRootNames artifacts)
                               name : names ->
                                 Task.throw (Exit.MakeNonMainFilesIntoJavaScript name names)
                           Just (Html target) ->
                             case platform of
                               Platform.Browser -> do
                                 name <- hasOneMain artifacts
-                                builder <- toBuilder root details desiredMode artifacts
-                                generate style target (Html.sandwich name builder) (NE.List name [])
+                                (JS.GeneratedResult source sourceMap) <- generate root details desiredMode artifacts
+                                writeToDisk style target (Html.sandwich name (SourceMap.sandwhich sourceMap source)) (NE.List name [])
                               _ -> do
                                 Task.throw Exit.MakeHtmlOnlyForBrowserPlatform
 
@@ -251,22 +253,22 @@ getNoMain modules root =
         Just _ -> Nothing
         Nothing -> Just name
 
--- GENERATE
+-- WRITE TO DISK
 
-generate :: Reporting.Style -> FilePath -> B.Builder -> NE.List ModuleName.Raw -> Task ()
-generate style target builder names =
+writeToDisk :: Reporting.Style -> FilePath -> B.Builder -> NE.List ModuleName.Raw -> Task ()
+writeToDisk style target builder names =
   Task.io $
     do
       Dir.createDirectoryIfMissing True (FP.takeDirectory target)
       File.writeBuilder target builder
       Reporting.reportGenerate style names target
 
--- TO BUILDER
+-- GENERATE
 
 data DesiredMode = Debug | Dev | Prod
 
-toBuilder :: FilePath -> Details.Details -> DesiredMode -> Build.Artifacts -> Task B.Builder
-toBuilder root details desiredMode artifacts =
+generate :: FilePath -> Details.Details -> DesiredMode -> Build.Artifacts -> Task JS.GeneratedResult
+generate root details desiredMode artifacts =
   Task.mapError Exit.MakeBadGenerate $
     case desiredMode of
       Debug -> Generate.debug root details artifacts