ppx: Investigate variants with payload

IDEAS.md

@@ -32,23 +32,30 @@ let trimContract: S.contract<string => string> = S.contract(s => {
 
 ## v5.2
 
+- S.matcher
 - ppx
+
+## v5.3
+
 - stop reallocate objects without transformations
-- S.matcher
+- Add `~space` to `S.jsonString` ?
+- Make S.serializeToString super fast
+- Add serialiseToString to js api
+- Make operations more treeshakable by starting passing the actual operation to the initialOperation function. Or add a condition (verify performance)
 - S.validateWith
-- S.toJSON/S.castToJson ???
-- nestedField for object
-- s.spread for object
-- S.produce
-- S.mutator
 
 ## v6
 
 - `S.json` -> `S.json(~unsafe: bool)` to improve tree-shaking
-- Add `~space` to `S.jsonString` ?
-- Make S.serializeToString super fast
-- Make operations more treeshakable by starting passing the actual operation to the initialOperation function. Or add a condition (verify performance)
 - Remove `s.failWithError` since there's `Error.raise` 🤔
-- Remove `S.classify` & `S.name` in favor of fields on `t` ???
 - Make `error.reason` tree-shakeable
 - Update `Literal` `tagged` to include `text`, `value` and `kind`. So it's more convinient and smaller bundle-size
+- Turn `String.email` -> `email`, `String.min` -> `stringMin` for tree-shaking
+
+## v???
+
+- S.toJSON/S.castToJson ???
+- nestedField for object
+- s.spread for object
+- S.produce
+- S.mutator

packages/ppx/src/ppx/variants.ml

@@ -3,8 +3,10 @@ open Parsetree
 open Ast_helper
 open Utils
 
-let parse_decl { pcd_name = { txt = name } } =
-  [%expr S.literal [%e Exp.construct (lid name) None]]
+let parse_decl { pcd_name = { txt = name; loc }; pcd_args } =
+  match pcd_args with
+  | Pcstr_tuple [] -> [%expr S.literal [%e Exp.construct (lid name) None]]
+  | _ -> fail loc "Variants with payload not supported yet"
 
 let generate_struct_expr constr_decls =
   let union_items = List.map parse_decl constr_decls in

packages/tests/src/ppx/Ppx_Variants_test.res

@@ -20,6 +20,14 @@ test("Variant with partial @as usage", t => {
 })
 
 // TODO: Support
-// type variantWithPayloads = One | Two(int) | Three(bool)
+// @struct
+// type variantWithPayloads = Constant | SinglePayload(int)
+// test("Variant with tuple payloads", t => {
+//   t->assertEqualStructs(
+//     variantWithPayloadsStruct,
+//     S.union([S.literal(Constant), S.unknown->Obj.magic]),
+//   )
+// })
+
 // TODO: Support @unboxed
 // TODO: Support @tag