[WIP] add record accessors support

src/Elm/AST/Canonical.elm

@@ -69,6 +69,7 @@ type Expr
     | Tuple LocatedExpr LocatedExpr
     | Tuple3 LocatedExpr LocatedExpr LocatedExpr
     | Record (Dict VarName (Binding LocatedExpr))
+    | RecordAccessor VarName
 
 
 {-| Discard the [location metadata](Elm.Data.Located#Located).
@@ -159,6 +160,9 @@ unwrap expr =
                     (always (Binding.map unwrap))
                     bindings
 
+        RecordAccessor name ->
+            Unwrapped.RecordAccessor name
+
 
 {-| Adds [**dummy** locations](Elm.Data.Located#dummyRegion) to the [Unwrapped.Expr](Elm.AST.Canonical.Unwrapped#Expr).
 -}
@@ -248,3 +252,6 @@ fromUnwrapped expr =
                     Dict.map
                         (always (Binding.map fromUnwrapped))
                         bindings
+
+            Unwrapped.RecordAccessor name ->
+                RecordAccessor name

src/Elm/AST/Canonical/Unwrapped.elm

@@ -38,3 +38,4 @@ type Expr
     | Tuple Expr Expr
     | Tuple3 Expr Expr Expr
     | Record (Dict VarName (Binding Expr))
+    | RecordAccessor VarName

src/Elm/AST/Frontend.elm

@@ -67,6 +67,7 @@ type Expr
     | Tuple LocatedExpr LocatedExpr
     | Tuple3 LocatedExpr LocatedExpr LocatedExpr
     | Record (List (Binding LocatedExpr))
+    | RecordAccessor VarName
 
 
 {-| A helper for the [Transform](/packages/Janiczek/transform/latest/) library.
@@ -150,6 +151,9 @@ recurse f expr =
         Record bindings ->
             Record <| List.map (Binding.map f_) bindings
 
+        RecordAccessor _ ->
+            expr
+
 
 {-| [Transform](/packages/Janiczek/transform/latest/Transform#transformAll)
 the expression using the provided function.
@@ -256,3 +260,6 @@ unwrap expr =
         Record bindings ->
             Unwrapped.Record <|
                 List.map (Binding.map unwrap) bindings
+
+        RecordAccessor name ->
+            Unwrapped.RecordAccessor name

src/Elm/AST/Frontend/Unwrapped.elm

@@ -36,3 +36,4 @@ type Expr
     | Tuple Expr Expr
     | Tuple3 Expr Expr Expr
     | Record (List (Binding Expr))
+    | RecordAccessor VarName

src/Elm/AST/Typed.elm

@@ -75,6 +75,7 @@ type Expr_
     | Tuple LocatedExpr LocatedExpr
     | Tuple3 LocatedExpr LocatedExpr LocatedExpr
     | Record (Dict VarName (Binding LocatedExpr))
+    | RecordAccessor VarName
 
 
 {-| A helper for the [Transform](/packages/Janiczek/transform/latest/) library.
@@ -165,6 +166,9 @@ recurse fn locatedExpr =
                                 (always (Binding.map fn))
                                 bindings
                             )
+
+                    RecordAccessor name ->
+                        expr
             )
 
 
@@ -256,6 +260,9 @@ recursiveChildren fn locatedExpr =
         Record bindings ->
             List.concatMap (.body >> fn) (Dict.values bindings)
 
+        RecordAccessor _ ->
+            []
+
 
 mapExpr : (Expr_ -> Expr_) -> LocatedExpr -> LocatedExpr
 mapExpr fn locatedExpr =
@@ -375,6 +382,9 @@ unwrap expr =
                 Dict.map
                     (always (Binding.map unwrap))
                     bindings
+
+        RecordAccessor name ->
+            Unwrapped.RecordAccessor name
     , type_
     )
 
@@ -463,4 +473,7 @@ dropTypes locatedExpr =
                     Record bindings ->
                         Canonical.Record <|
                             Dict.map (always (Binding.map dropTypes)) bindings
+
+                    RecordAccessor name ->
+                        Canonical.RecordAccessor name
             )

src/Elm/AST/Typed/Unwrapped.elm

@@ -44,3 +44,4 @@ type Expr_
     | Tuple Expr Expr
     | Tuple3 Expr Expr Expr
     | Record (Dict VarName (Binding Expr))
+    | RecordAccessor VarName

src/Elm/Data/Type.elm

@@ -24,6 +24,7 @@ type Type
     | Tuple Type Type
     | Tuple3 Type Type Type
     | Record (Dict VarName Type)
+    | ExtensibleRecord ( VarName, Type ) (Dict VarName Type) -- An extensible record has at least a binding
     | {- The actual definitions of type aliases and custom types are elsewhere
          (in the Declaration module), this is just a "pointer", "var".
 

src/Elm/Data/Type/ToString.elm

@@ -183,6 +183,26 @@ toString state type_ =
             else
                 ( "{ " ++ bindingsStr ++ " }", state1 )
 
+        ExtensibleRecord firstBinding otherBindings ->
+            let
+                ( bindingsStr, state1 ) =
+                    List.foldr
+                        (\param ( acc, state2 ) ->
+                            let
+                                ( string, state3 ) =
+                                    niceRecordBinding state2 param
+                            in
+                            ( string :: acc, state3 )
+                        )
+                        ( [], state )
+                        (firstBinding :: Dict.toList otherBindings)
+                        |> Tuple.mapFirst (String.join ", ")
+
+                ( newName, newState ) =
+                    getFreeName state1
+            in
+            ( "{ " ++ newName ++ " | " ++ bindingsStr ++ " }", newState )
+
 
 getName : State -> Int -> ( String, State )
 getName ((State { counter, mapping }) as state) varId =
@@ -203,6 +223,11 @@ getName ((State { counter, mapping }) as state) varId =
             )
 
 
+getFreeName : State -> ( String, State )
+getFreeName (State r) =
+    ( niceVarName r.counter, State { r | counter = r.counter + 1 } )
+
+
 {-| Function to get from a number to a nice type variable name.
 It follows this sequence:
 
@@ -322,3 +347,6 @@ shouldWrapParens type_ =
 
         Record _ ->
             False
+
+        ExtensibleRecord _ _ ->
+            False

src/Stage/Desugar.elm

@@ -196,6 +196,9 @@ desugarExpr modules thisModule located =
                                     |> Canonical.Record
                             )
 
+        Frontend.RecordAccessor name ->
+            return <| Canonical.RecordAccessor name
+
 
 
 -- HELPERS