Proof of Concept: explore per-file custom infix operators.

Add support for `@@infix.add` and `@@infix.remove`.

Author: cristianoc

res_syntax/src/res_core.ml

@@ -6420,7 +6420,7 @@ and parseStandaloneAttribute p =
       p.uncurried_config <- Res_uncurried.Default;
       attrId
     | "toUncurried" -> {attrId with txt = "uncurried"}
-    | "infix" -> (
+    | "infix" | "infix.add" | "infix.remove" -> (
       match payload with
       | PStr
           [
@@ -6441,9 +6441,12 @@ and parseStandaloneAttribute p =
                     _ );
             };
           ] ->
-        p.scanner.customInfix <-
-          p.scanner.customInfix |> Res_custom_infix.addSymbol ~name ~alias;
-        attrId
+        if attrId.txt <> "infix.add" then
+          p.scanner.customInfix <-
+            p.scanner.customInfix |> Res_custom_infix.addSymbol ~name ~alias;
+
+        if attrId.txt = "infix.remove" then attrId
+        else {attrId with txt = "infix"}
       | _ ->
         Parser.err ~startPos ~endPos:p.startPos p
           (Diagnostics.message

res_syntax/src/res_custom_infix.ml

@@ -4,6 +4,8 @@ let addSymbol ~name ~alias x = (name, alias) :: x
 
 let findAlias ~alias x = x |> List.find_opt (fun (_, a) -> alias = a)
 
+let removeName ~name x = x |> List.filter (fun (n, _) -> n <> name)
+
 let lookupName ~name ~src ~srcLen ~offset =
   let nameLen = String.length name in
   let restLen = srcLen - offset in

res_syntax/src/res_printer.ml

@@ -5279,7 +5279,7 @@ and printAttribute ?(standalone = false) ~state
       | "toUncurried" ->
         state.uncurried_config <- Res_uncurried.Default;
         {id with txt = "uncurried"}
-      | "infix" -> (
+      | "infix" | "infix.add" | "infix.remove" -> (
         match payload with
         | PStr
             [
@@ -5303,9 +5303,13 @@ and printAttribute ?(standalone = false) ~state
                       _ );
               };
             ] ->
-          state.customInfix <-
-            state.customInfix |> Res_custom_infix.addSymbol ~name ~alias;
-          id
+          if id.txt = "infix.remove" then
+            state.customInfix <-
+              state.customInfix |> Res_custom_infix.removeName ~name
+          else
+            state.customInfix <-
+              state.customInfix |> Res_custom_infix.addSymbol ~name ~alias;
+          if id.txt = "infix.add" then {id with txt = "infix"} else id
         | _ -> (* should never happpen *) id)
       | _ -> id
     in

res_syntax/tests/printer/expr/expected/infixAdd.res.txt

@@ -0,0 +1,7 @@
+let plus = (x, y) => x + y
+let minus = (x, y) => x - y
+
+@@infix(("😀", "plus"))
+@@infix(("💩💩", "minus"))
+
+let q = 3 😀 4 💩💩 5

res_syntax/tests/printer/expr/expected/infixRemove.res.txt

@@ -0,0 +1,7 @@
+let plus = (x, y) => x + y
+let minus = (x, y) => x - y
+
+@@infix.remove(("😀", "plus"))
+@@infix.remove(("💩💩", "minus"))
+
+let q = minus(plus(3, 4), 5)

res_syntax/tests/printer/expr/expected/infixScope.res.txt

@@ -0,0 +1,7 @@
+module M = {
+  @@infix(("+++", "+"))
+
+  let z = 3 +++ 4
+}
+
+let z = 3 + 4

res_syntax/tests/printer/expr/infixAdd.res

@@ -0,0 +1,7 @@
+let plus = (x, y) => x + y
+let minus = (x, y) => x - y
+
+@@infix.add(("😀", "plus"))
+@@infix.add(("💩💩", "minus"))
+
+let q = minus(plus(3, 4), 5)

res_syntax/tests/printer/expr/infixRemove.res

@@ -0,0 +1,7 @@
+let plus = (x, y) => x + y
+let minus = (x, y) => x - y
+
+@@infix.remove(("😀", "plus"))
+@@infix.remove(("💩💩", "minus"))
+
+let q = 3 😀 4 💩💩 5

res_syntax/tests/printer/expr/infixScope.res

@@ -0,0 +1,8 @@
+
+module M = {
+    @@infix.add(("+++", "+"))
+
+    let z = 3 + 4
+}
+
+let z = 3 + 4