0.19 upgrade: replace Basics.flip

elm-format.cabal

@@ -94,6 +94,7 @@ library
         ElmFormat.InputConsole
         ElmFormat.Operation
         ElmFormat.OutputConsole
+        ElmFormat.Upgrade_0_19
         ElmFormat.Version
         Flags
         Messages.Formatter.Format

src/ElmFormat/Render/Box.hs

@@ -21,6 +21,7 @@ import Data.Maybe (fromMaybe, maybeToList)
 import qualified Data.Text as Text
 import qualified ElmFormat.Render.ElmStructure as ElmStructure
 import qualified ElmFormat.Render.Markdown
+import qualified ElmFormat.Upgrade_0_19 as Upgrade_0_19
 import qualified ElmFormat.Version
 import qualified ElmVersion
 import qualified Parse.Parse as Parse
@@ -972,6 +973,13 @@ expressionParens inner outer =
 
 formatExpression :: ElmVersion -> ExpressionContext -> AST.Expression.Expr -> Box
 formatExpression elmVersion context aexpr =
+    case elmVersion of
+        Elm_0_19_Upgrade -> formatExpression' elmVersion context (Upgrade_0_19.transform aexpr)
+        _ -> formatExpression' elmVersion context aexpr
+
+
+formatExpression' :: ElmVersion -> ExpressionContext -> AST.Expression.Expr -> Box
+formatExpression' elmVersion context aexpr =
     case RA.drop aexpr of
         AST.Expression.Literal lit ->
             formatLiteral elmVersion lit

src/ElmFormat/Upgrade_0_19.hs

@@ -0,0 +1,85 @@
+{-# OPTIONS_GHC -Wall #-}
+module ElmFormat.Upgrade_0_19 (transform) where
+
+import AST.V0_16
+import AST.Expression
+import AST.Pattern
+import AST.Variable
+import Reporting.Annotation (Located(A))
+
+import qualified Reporting.Annotation as RA
+import qualified Reporting.Region as Region
+
+
+transform :: Expr -> Expr
+transform expr =
+    case RA.drop expr of
+        VarExpr var | isBasics "flip" var ->
+            noRegion $ Lambda
+                [makeArg "f", makeArg "b", makeArg "a"] []
+                (noRegion $ App
+                    (makeVarRef "f")
+                    [([], makeVarRef "a"), ([], makeVarRef "b")]
+                    (FAJoinFirst JoinAll)
+                )
+                False
+
+        App (A _ (VarExpr var)) [(pre, arg1)] _ | isBasics "flip" var ->
+            noRegion $ Lambda
+                [makeArg "b", makeArg "a"] pre
+                (noRegion $ App
+                    arg1
+                    [([], makeVarRef "a"), ([], makeVarRef "b")]
+                    (FAJoinFirst JoinAll)
+                )
+                False
+
+        App (A _ (VarExpr var)) [(pre, arg1), arg2] _ | isBasics "flip" var ->
+            noRegion $ Lambda
+                [makeArg "a"] pre
+                (noRegion $ App
+                    arg1
+                    [([], makeVarRef "a"), arg2]
+                    (FAJoinFirst JoinAll)
+                )
+                False
+
+        App (A _ (VarExpr var)) ((pre, arg1):arg2:arg3:argRest) multiline | isBasics "flip" var ->
+            noRegion $ Parens
+                (Commented pre (noRegion $ App arg1 (arg3:arg2:argRest) multiline) [])
+
+        _ ->
+            expr
+
+
+--
+-- Generic helpers
+--
+
+
+nowhere :: Region.Position
+nowhere =
+    Region.Position 0 0
+
+
+noRegion :: a -> RA.Located a
+noRegion =
+    RA.at nowhere nowhere
+
+
+isBasics :: String -> Ref -> Bool
+isBasics targetName var =
+    case var of
+        VarRef [] (LowercaseIdentifier name) | name == targetName -> True
+        VarRef [(UppercaseIdentifier "Basics")] (LowercaseIdentifier name) | name == targetName -> True
+        _ -> False
+
+
+makeArg :: String -> (Comments, Pattern)
+makeArg varName =
+    ([], noRegion $ VarPattern $ LowercaseIdentifier varName)
+
+
+makeVarRef :: String -> Expr
+makeVarRef varName =
+    noRegion $ VarExpr $ VarRef [] $ LowercaseIdentifier varName

tests/run-tests.sh

@@ -307,6 +307,11 @@ checkWaysToRun
 
 checkGood 0.19 AllSyntax/0.19/Literals.elm
 
+checkUpgrade 0.19 Elm-0.19/CommaFunctionsBecomeLambdas.elm
+checkUpgrade 0.19 Elm-0.19/RemoveBangOperator.elm
+checkUpgrade 0.19 Elm-0.19/NewStringEscapeSyntax.elm
+checkUpgrade 0.19 Elm-0.19/RemoveBasicsFlip.elm
+
 checkGood 0.18 Simple.elm
 checkGood 0.18 AllSyntax/0.18/AllSyntax.elm
 checkGoodAllSyntax 0.18 Module
@@ -383,10 +388,6 @@ checkUpgrade 0.18 Elm-0.18/BackticksBecomeFunctionCalls.elm
 checkUpgrade 0.18 Elm-0.18/SpecialBackticksBecomePipelines.elm
 checkUpgrade 0.18 Elm-0.18/RenameTupleFunctions.elm
 
-checkUpgrade 0.19 Elm-0.19/CommaFunctionsBecomeLambdas.elm
-checkUpgrade 0.19 Elm-0.19/RemoveBangOperator.elm
-checkUpgrade 0.19 Elm-0.19/NewStringEscapeSyntax.elm
-
 checkValidationOutputFormat
 
 echo

tests/test-files/transform/Elm-0.19/RemoveBasicsFlip.elm

@@ -0,0 +1,10 @@
+fullyApplied f = flip f "2" 1
+fullyApplied_comments f = flip{-A-}f{-B-}"2"{-C-}1
+partiallyApplied f = flip f "2"
+partiallyApplied_comments f = flip{-A-}f{-B-}"2"
+functionOnly f = flip f
+functionOnly_comments f = flip{-A-}f
+unapplied = flip
+extraArgs f = flip f 1 2 3 4 5
+
+qualified f = Basics.flip f "2" 1

tests/test-files/transform/Elm-0.19/RemoveBasicsFlip.formatted.elm

@@ -0,0 +1,41 @@
+module Main exposing (..)
+
+
+fullyApplied f =
+    f 1 "2"
+
+
+fullyApplied_comments f =
+    ({- A -} f {- C -} 1 {- B -} "2")
+
+
+partiallyApplied f =
+    \a -> f a "2"
+
+
+partiallyApplied_comments f =
+    \a ->
+        {- A -}
+        f a {- B -} "2"
+
+
+functionOnly f =
+    \b a -> f a b
+
+
+functionOnly_comments f =
+    \b a ->
+        {- A -}
+        f a b
+
+
+unapplied =
+    \f b a -> f a b
+
+
+extraArgs f =
+    f 2 1 3 4 5
+
+
+qualified f =
+    f 1 "2"