[#345] Use mixins approach for a custom prelude by default (#415)

* [#345] Use `mixins` approach for a custom prelude by default Resolves #345 * Remove Prelude module generation
kowainik · Feb 21, 2020 · e1c7b55 · e1c7b55
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -38,6 +38,16 @@ The changelog is available [on GitHub][2].
     ghc-options:       -Wmissing-deriving-strategies
   ```
 
+  (by [@chshersh](https://github.com/chshersh))
+* [#345](https://github.com/kowainik/summoner/issues/345):
+  Apply `mixins` approach for using alternative preludes instead of
+  the `base-noprelude` trick. Now it looks like this in the `.cabal`
+  file:
+
+  ```haskell
+  mixins:              base hiding (Prelude)
+                     , relude (Relude as Prelude)
+  ```
   (by [@chshersh](https://github.com/chshersh))
 * Use `colourista` for pretty terminal formatting.
   (by [@chshersh](https://github.com/chshersh))

diff --git a/README.md b/README.md
@@ -86,8 +86,7 @@ Features related to the structure and content of the generated projects.
 + Ability to pick stanzas (library, executable, test-suite, benchmark).
 + Usage of [common stanza](https://vrom911.github.io/blog/common-stanzas) to reduce `.cabal` file's boilerplate.
 + Option to include an alternative prelude, if desired. The project would then
-  use [`base-noprelude` technique](http://hackage.haskell.org/package/Prelude),
-  and the `Prelude` module would be added to the library target.
+  use the [`mixins` technique](https://www.reddit.com/r/haskelltil/comments/9qa366/easy_way_to_replace_default_prelude_with_the/).
 + Whole Hackage-upload checklist support (exhaustive `.cabal` file, PVP versioning, GHC options, conventional meta files).
 + Support for multiple GHC versions, with thoughtful reflection on project meta, base versions (e.g. `base >= 4.9 && < 4.12`), etc.
 + Ability to create runnable Haskell scripts.

diff --git a/summoner-cli/src/Summoner/Project.hs b/summoner-cli/src/Summoner/Project.hs
@@ -97,9 +97,6 @@ generateProject isOffline projectName Config{..} = do
     settingsTest      <- decisionToBool cTest (mkDefaultYesNoPrompt "tests")
     settingsBench     <- decisionToBool cBench (mkDefaultYesNoPrompt "benchmarks")
     settingsPrelude   <- if settingsIsLib then getPrelude else pure Nothing
-    let settingsBaseType = case settingsPrelude of
-            Nothing -> "base"
-            Just _  -> "base-noprelude"
 
     let settingsExtensions = cExtensions
     let settingsGhcOptions = cGhcOptions

diff --git a/summoner-cli/src/Summoner/Settings.hs b/summoner-cli/src/Summoner/Settings.hs
@@ -43,7 +43,6 @@ data Settings = Settings
     , settingsTest           :: !Bool   -- ^ add tests
     , settingsBench          :: !Bool   -- ^ add benchmarks
     , settingsTestedVersions :: ![GhcVer]  -- ^ GHC versions
-    , settingsBaseType       :: !Text -- ^ Base library to use
     , settingsPrelude        :: !(Maybe CustomPrelude)  -- ^ custom prelude to be used
     , settingsExtensions     :: ![Text] -- ^ default extensions
     , settingsGhcOptions     :: ![Text] -- ^ default GHC options

diff --git a/summoner-cli/src/Summoner/Template/Cabal.hs b/summoner-cli/src/Summoner/Template/Cabal.hs
@@ -91,9 +91,8 @@ cabalFile Settings{..} = File (toString settingsRepo ++ ".cabal") cabalFileConte
         [text|
         $endLine
         common common-options
-          build-depends:       $settingsBaseType $baseBounds
-                             $commaPreludeLibrary
-
+          build-depends:       base $baseBounds
+          $customPrelude
           $ghcOptions
 
           default-language:    Haskell2010
@@ -138,7 +137,6 @@ cabalFile Settings{..} = File (toString settingsRepo ++ ".cabal") cabalFileConte
           import:              common-options
           hs-source-dirs:      src
           exposed-modules:     $libModuleName
-                               $preludeMod
         |]
 
     executableStanza :: Text
@@ -195,10 +193,17 @@ cabalFile Settings{..} = File (toString settingsRepo ++ ".cabal") cabalFileConte
                              -with-rtsopts=-N
         |]
 
-    preludeMod, commaPreludeLibrary :: Text
-    (preludeMod, commaPreludeLibrary) = case settingsPrelude of
-        Nothing                -> ("", "")
-        Just CustomPrelude{..} -> ("Prelude", ", " <> cpPackage)
+    customPrelude :: Text
+    customPrelude = case settingsPrelude of
+        Nothing -> ""
+        Just CustomPrelude{..} ->
+            "                   , " <> cpPackage <> "\n" <>
+            [text|
+            $endLine
+            mixins:              base hiding (Prelude)
+                               , $cpPackage ($cpModule as Prelude)
+            $endLine
+            |]
 
     defaultExtensions :: Text
     defaultExtensions = case settingsExtensions of

diff --git a/summoner-cli/src/Summoner/Template/Haskell.hs b/summoner-cli/src/Summoner/Template/Haskell.hs
@@ -14,18 +14,17 @@ module Summoner.Template.Haskell
 
 import NeatInterpolation (text)
 
-import Summoner.CustomPrelude (CustomPrelude (..))
 import Summoner.Settings (Settings (..))
 import Summoner.Text (packageToModule)
 import Summoner.Tree (TreeFs (..))
 
 
 haskellFiles :: Settings -> [TreeFs]
 haskellFiles Settings{..} = concat
-    [ [ Dir "src"     $ libFile : preludeFile   | settingsIsLib ]
-    , [ Dir "app"       [exeFile]               | settingsIsExe ]
-    , [ Dir "test"      [testFile]              | settingsTest  ]
-    , [ Dir "benchmark" [benchmarkFile]         | settingsBench ]
+    [ [ Dir "src"       [libFile]       | settingsIsLib ]
+    , [ Dir "app"       [exeFile]       | settingsIsExe ]
+    , [ Dir "test"      [testFile]      | settingsTest  ]
+    , [ Dir "benchmark" [benchmarkFile] | settingsBench ]
     ] ++ maybeToList (File ".stylish-haskell.yaml" <$> settingsStylish)
   where
     libFile :: TreeFs
@@ -54,19 +53,6 @@ haskellFiles Settings{..} = concat
     licenseName :: Text
     licenseName = show settingsLicenseName
 
-    preludeFile :: [TreeFs]
-    preludeFile = maybeToList $
-        settingsPrelude <&> \CustomPrelude{..} -> File "Prelude.hs"
-            [text|
-            -- | Uses [$cpPackage](https://hackage.haskell.org/package/${cpPackage}) as default Prelude.
-
-            module Prelude
-                   ( module $cpModule
-                   ) where
-
-            import $cpModule
-            |]
-
     exeFile :: TreeFs
     exeFile = File "Main.hs" $ if settingsIsLib then createExe else createOnlyExe
 

diff --git a/summoner-cli/src/Summoner/Template/Stack.hs b/summoner-cli/src/Summoner/Template/Stack.hs
@@ -11,7 +11,7 @@ module Summoner.Template.Stack
        ) where
 
 import Summoner.Default (defaultGHC)
-import Summoner.GhcVer (GhcVer (..), baseVer, latestLts, showGhcVer)
+import Summoner.GhcVer (GhcVer (..), latestLts, showGhcVer)
 import Summoner.Settings (Settings (..))
 import Summoner.Tree (TreeFs (..))
 
@@ -22,14 +22,9 @@ stackFiles Settings{..} = map createStackYaml settingsTestedVersions
     -- create @stack.yaml@ file with LTS corresponding to specified ghc version
     createStackYaml :: GhcVer -> TreeFs
     createStackYaml ghcV = File (toString $ "stack" <> ver <> ".yaml")
-        $ "resolver: " <> latestLts ghcV <> extraDeps
+        $ "resolver: " <> latestLts ghcV <> "\n"
       where
         ver :: Text
         ver = if ghcV == defaultGHC
               then ""
               else "-" <> showGhcVer ghcV
-
-        extraDeps :: Text
-        extraDeps = case settingsPrelude of
-            Nothing -> ""
-            Just _  -> "\n\nextra-deps: [base-noprelude-" <> baseVer ghcV <> "]"
diff --git a/summoner-cli/test/Test/Golden.hs b/summoner-cli/test/Test/Golden.hs
@@ -82,7 +82,6 @@ fullProject = Settings
     , settingsTest           = True
     , settingsBench          = True
     , settingsTestedVersions = [Ghc802 .. defaultGHC]
-    , settingsBaseType       = "base-noprelude"
     , settingsPrelude        = Just $ CustomPrelude "relude" "Relude"
     , settingsExtensions     = ["ConstraintKinds", "LambdaCase", "OverloadedStrings"]
     , settingsGitignore      = [".secret"]
@@ -144,7 +143,6 @@ smallProject = Settings
     , settingsTest           = False
     , settingsBench          = False
     , settingsTestedVersions = [defaultGHC]
-    , settingsBaseType       = "base"
     , settingsPrelude        = Nothing
     , settingsExtensions     = []
     , settingsGhcOptions     = []

diff --git a/summoner-cli/test/golden/fullProject/fullProject.cabal b/summoner-cli/test/golden/fullProject/fullProject.cabal
@@ -25,9 +25,12 @@ source-repository head
   location:            https://github.com/kowainik/fullProject.git
 
 common common-options
-  build-depends:       base-noprelude >= 4.9.1.0 && < 4.14
+  build-depends:       base >= 4.9.1.0 && < 4.14
                      , relude
-
+
+  mixins:              base hiding (Prelude)
+                     , relude (Relude as Prelude)
+
   ghc-options:         -Wcompat
                        -Widentities
 
@@ -40,7 +43,6 @@ library
   import:              common-options
   hs-source-dirs:      src
   exposed-modules:     FullProject
-                       Prelude
 
 executable fullProject
   import:              common-options

diff --git a/summoner-cli/test/golden/fullProject/src/Prelude.hs b/summoner-cli/test/golden/fullProject/src/Prelude.hs
diff --git a/summoner-cli/test/golden/fullProject/stack-8.0.2.yaml b/summoner-cli/test/golden/fullProject/stack-8.0.2.yaml
@@ -1,3 +1 @@
 resolver: lts-9.21
-
-extra-deps: [base-noprelude-4.9.1.0]
diff --git a/summoner-cli/test/golden/fullProject/stack-8.2.2.yaml b/summoner-cli/test/golden/fullProject/stack-8.2.2.yaml
@@ -1,3 +1 @@
 resolver: lts-11.22
-
-extra-deps: [base-noprelude-4.10.1.0]
diff --git a/summoner-cli/test/golden/fullProject/stack-8.4.4.yaml b/summoner-cli/test/golden/fullProject/stack-8.4.4.yaml
@@ -1,3 +1 @@
 resolver: lts-12.26
-
-extra-deps: [base-noprelude-4.11.1.0]
diff --git a/summoner-cli/test/golden/fullProject/stack-8.6.5.yaml b/summoner-cli/test/golden/fullProject/stack-8.6.5.yaml
@@ -1,3 +1 @@
 resolver: lts-14.27
-
-extra-deps: [base-noprelude-4.12.0.0]
diff --git a/summoner-cli/test/golden/fullProject/stack.yaml b/summoner-cli/test/golden/fullProject/stack.yaml
@@ -1,3 +1 @@
 resolver: lts-15.0
-
-extra-deps: [base-noprelude-4.13.0.0]
diff --git a/summoner-cli/test/golden/smallProject/smallProject.cabal b/summoner-cli/test/golden/smallProject/smallProject.cabal
@@ -14,8 +14,7 @@ tested-with:         GHC == 8.8.2
 
 common common-options
   build-depends:       base ^>= 4.13.0.0
-
-
+
   ghc-options:         -Wall
                        -Wcompat
                        -Widentities

diff --git a/summoner-tui/src/Summoner/Tui/Kit.hs b/summoner-tui/src/Summoner/Tui/Kit.hs
@@ -182,7 +182,6 @@ summonKitToSettings sk = Settings
     , settingsTest           = sk ^. projectMeta . test
     , settingsBench          = sk ^. projectMeta . bench
     , settingsTestedVersions = sortNub $ defaultGHC : (sk ^. projectMeta . ghcs)
-    , settingsBaseType       = baseT
     , settingsPrelude        = cP
     , settingsExtensions     = sk ^. extensions
     , settingsGhcOptions     = sk ^. ghcOptions
@@ -198,14 +197,13 @@ summonKitToSettings sk = Settings
     isGitHub :: Bool
     isGitHub = sk ^. gitHub . enabled
 
-    baseT :: Text
     cP ::  Maybe CustomPrelude
-    (baseT, cP) =
+    cP =
         let cpPackage = T.strip $ sk ^. projectMeta . preludeName
             cpModule  = T.strip $ sk ^. projectMeta . preludeModule
         in if ("" /= cpPackage) && ("" /= cpModule)
-           then ("base-noprelude", Just CustomPrelude{..})
-           else ("base", Nothing)
+           then Just CustomPrelude{..}
+           else Nothing
 
 -- | Gets 'Settings' on successful application complition.
 finalSettings :: SummonKit -> IO Settings
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1 @@
		resolver: lts-9.21

		extra-deps: [base-noprelude-4.9.1.0]
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1 @@
		resolver: lts-11.22

		extra-deps: [base-noprelude-4.10.1.0]
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1 @@
		resolver: lts-12.26

		extra-deps: [base-noprelude-4.11.1.0]
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1 @@
		resolver: lts-14.27

		extra-deps: [base-noprelude-4.12.0.0]
Original file line number	Diff line number	Diff line change
		@@ -1,3 +1 @@
		resolver: lts-15.0

		extra-deps: [base-noprelude-4.13.0.0]