Replace Dhall with TOML using toml-reader (#120)

Co-authored-by: Ollie Charles <ollie@ocharles.org.uk>

.github/workflows/nix-build.yml

@@ -4,18 +4,18 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v3.5.3
       with:
           persist-credentials: false
           submodules: true
 
-    - uses: cachix/install-nix-action@v14.1
+    - uses: cachix/install-nix-action@v22
       with:
         nix_path: nixpkgs=channel:nixos-unstable
         extra_nix_config: |
           trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
           substituters = https://cache.nixos.org/ https://cache.iog.io
-    - uses: cachix/cachix-action@v10
+    - uses: cachix/cachix-action@v12
       with:
         name: weeder
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'

README.md

@@ -18,9 +18,9 @@ code is reachable and which code is dead.
 
 ## Preparing Your Code for Weeder
 
-To use Weeder, you will need to generate `.hie` files from your source code. 
+To use Weeder, you will need to generate `.hie` files from your source code.
 
-### Cabal 
+### Cabal
 
 If you use Cabal, this is easily done by adding one line to your
 `cabal.project.local` file:
@@ -55,13 +55,8 @@ stack build
 
 ## Calling Weeder
 
-To call Weeder, you first need to provide a configuration file, `weeder.dhall`. Weeder uses
-[Dhall](https://dhall-lang.org) as its configuration format, and configuration
-files have the type:
-
-``` dhall
-{ roots : List Text, type-class-roots : Bool }
-```
+To call Weeder, you first need to provide a configuration file, `weeder.toml`. Weeder uses
+[TOML](https://toml.io/en/) as its configuration format.
 
 `roots` is a list of regular expressions of symbols that are considered as
 alive. If you're building an executable, the pattern `^Main.main$` is a
@@ -74,8 +69,9 @@ a type class instance as a root. Weeder is currently unable to add dependency
 edges into type class instances, and without this flag may produce false
 positives. It's recommended to initially set this to `True`:
 
-``` dhall
-{ roots = [ "^Main.main$" ], type-class-roots = True }
+``` toml
+roots = [ "^Main.main$" ]
+type-class-roots = true
 ```
 
 Now invoke the `weeder` executable, and - if your project has weeds - you will
@@ -93,7 +89,7 @@ in the Dhall project).
 
 # Tips
 
-- You may want to add `^Paths_.*` to the roots in `weeder.dhall` to ignore the
+- You may want to add `^Paths_.*` to the roots in `weeder.toml` to ignore the
   `Paths_packageName` module automatically generated by Cabal.
 
 # Limitations

cabal.project

@@ -1,10 +1,2 @@
 packages:
   weeder.cabal
-
--- https://github.com/well-typed/cborg/pull/304
-source-repository-package
-  type: git
-  location: https://github.com/scarf-sh/cborg
-  tag: 8dae0d21e6f17e30785f35bb3ef5eb611863a904
-  subdir: cborg
-  --sha256: sha256-SAHFIlN5QKQKJFhHliXvXOQhrqvsE/TLvY2rkftXkHM=

src/Weeder/Config.hs

@@ -3,14 +3,13 @@
 {-# language OverloadedStrings #-}
 {-# language RecordWildCards #-}
 
-module Weeder.Config ( Config(..), config ) where
+module Weeder.Config ( Config(..) ) where
 
 -- containers
 import Data.Set ( Set )
-import qualified Data.Set as Set
 
--- dhall
-import qualified Dhall
+-- toml-reader
+import qualified TOML
 
 
 -- | Configuration for Weeder analysis.
@@ -24,14 +23,9 @@ data Config = Config
     -- instance is used - enabling this option can prevent false positives.
   }
 
-
--- | A Dhall expression decoder for 'Config'.
---
--- This parses Dhall expressions of the type @{ roots : List Text, type-class-roots : Bool }@.
-config :: Dhall.Decoder Config
-config =
-  Dhall.record do
-    rootPatterns <- Set.fromList <$> Dhall.field "roots" ( Dhall.list Dhall.string )
-    typeClassRoots <- Dhall.field "type-class-roots" Dhall.bool
+instance TOML.DecodeTOML Config where
+  tomlDecoder = do
+    rootPatterns <- TOML.getField "roots"
+    typeClassRoots <- TOML.getField "type-class-roots"
 
     return Config{..}

src/Weeder/Main.hs

@@ -9,6 +9,7 @@
 module Weeder.Main ( main, mainWithConfig ) where
 
 -- base
+import Control.Exception ( throwIO )
 import Control.Monad ( guard, unless, when )
 import Control.Monad.IO.Class ( liftIO )
 import Data.Bool
@@ -24,8 +25,8 @@ import qualified Data.Set as Set
 -- text
 import qualified Data.Text as T
 
--- dhall
-import qualified Dhall
+-- toml-reader
+import qualified TOML
 
 -- directory
 import System.Directory ( canonicalizePath, doesDirectoryExist, doesFileExist, doesPathExist, listDirectory, withCurrentDirectory )
@@ -63,15 +64,16 @@ main = do
     execParser $
       info (optsP <**> helper <**> versionP) mempty
 
-  Dhall.input config configExpr
+  TOML.decodeFile (T.unpack configExpr)
+    >>= either throwIO pure
     >>= mainWithConfig hieExt hieDirectories requireHsFiles
   where
     optsP = (,,,)
         <$> strOption
             ( long "config"
-                <> help "A Dhall expression for Weeder's configuration. Can either be a file path (a Dhall import) or a literal Dhall expression."
-                <> value "./weeder.dhall"
-                <> metavar "<weeder.dhall>"
+                <> help "A file path for Weeder's configuration."
+                <> value "./weeder.toml"
+                <> metavar "<weeder.toml>"
                 <> showDefaultWith T.unpack
             )
         <*> strOption

weeder.cabal

@@ -22,7 +22,6 @@ library
     , base                 ^>= 4.17.0.0
     , bytestring           ^>= 0.10.9.0 || ^>= 0.11.0.0
     , containers           ^>= 0.6.2.1
-    , dhall                ^>= 1.30.0 || ^>= 1.31.0 || ^>= 1.32.0 || ^>= 1.33.0 || ^>= 1.34.0 || ^>= 1.35.0 || ^>= 1.36.0 || ^>= 1.37.0 || ^>= 1.40.0 || ^>= 1.41
     , directory            ^>= 1.3.3.2
     , filepath             ^>= 1.4.2.1
     , generic-lens         ^>= 2.2.0.0
@@ -32,6 +31,7 @@ library
     , optparse-applicative ^>= 0.14.3.0 || ^>= 0.15.1.0 || ^>= 0.16.0.0 || ^>=  0.17
     , regex-tdfa           ^>= 1.2.0.0 || ^>= 1.3.1.0
     , text                 ^>= 2.0.1
+    , toml-reader          ^>= 0.2.0.0
     , transformers         ^>= 0.5.6.2 || ^>= 0.6
   hs-source-dirs: src
   exposed-modules:

weeder.dhall

@@ -1,3 +0,0 @@
-{ roots = [ "Main.main", "^Paths_weeder\\..*" ]
-, type-class-roots = True
-}

weeder.toml

@@ -0,0 +1,2 @@
+roots = [ "Main.main", "^Paths_weeder\\..*" ]
+type-class-roots = true