Submodule functor call is curried, but the target function is uncurried

[dsiu]

I am porting bs-bastet to modern ReScript (v12+) (WIP at https://github.com/dsiu/rescript-bastet/tree/rescript-v12)

In rescript@12.0.0-alpha.7 (alpha.4 and later), the generated js for nested module functor invocation is incorrect.

The line:

let EQ = M.Eq(IntEq)(ArbitraryInt);

is assuming M.eq is curried while M.eq is defined as:

function Eq(E, A) {
  let suite = name => "suite: " + name;
  return {
    suite: suite
  };
}

let M = {
  Eq: Eq
};

which clearly isn't curried.

The error is:

{
  "message":"M.Eq(IntEq) is not a function. (In 'M.Eq(IntEq)(ArbitraryInt)', 'M.Eq(IntEq)' is an instance of Object)",
  "line":54,
  "column":21,
  "stack":"eval code@\neval@[native code]\n@about:srcdoc:39:20"
}

In rescript@11, the error line was compiled to :

let EQ = Curry._2(Eq, IntEq, ArbitraryInt);

which runs correctly.

Playground link for test code

Test Code

module type TEST = {
  type test
}

module type ARBITRARY = {
  type t
  type arbitrary<'a>
}

module type QUICKCHECK = {
  type t
  type arbitrary<'a>
}

module Interface = {
  module type EQ = {
    type t

    let eq: (t, t) => bool
  }
}

module Make = (T: TEST, Q: QUICKCHECK with type t = T.test) => {
  type t
  type arbitrary<'a>

  module Eq = (
    E: Interface.EQ,
    A: ARBITRARY with type t := E.t and type arbitrary<'a> := Q.arbitrary<'a>,
  ) => {
    let suite = name => "suite: " ++ name
  }
}

module IntWithTest = (
  T: TEST,
  Q: QUICKCHECK with type t = T.test,
  A: ARBITRARY with type t := int and type arbitrary<'a> := Q.arbitrary<'a>,
) => {
  module IntEq: Interface.EQ = {
    type t = int

    let eq = (a, b) => Int.equal(a, b)
  }
  module M = Make(T, Q)
  module EQ = M.Eq(IntEq, A)
}

module ArbitraryInt: ARBITRARY with type t = int and type arbitrary<'a> = array<'a> = {
  type t = int
  type arbitrary<'a> = array<'a>
}

module JsQuickCheck = {
  type t = int
  type arbitrary<'a> = array<'a>
}

module MochaTest = {
  type test = int
}

module TestInt = IntWithTest(MochaTest, JsQuickCheck, ArbitraryInt)

TestInt.EQ.suite->Console.log

// Generated by ReScript, PLEASE EDIT WITH CARE


let Interface = {};

function Make(T, Q) {
  let Eq = (E, A) => {
    let suite = name => "suite: " + name;
    return {
      suite: suite
    };
  };
  return {
    Eq: Eq
  };
}

function IntWithTest(T, Q, A) {
  let eq = (a, b) => a === b;
  let IntEq = {
    eq: eq
  };
  let Eq = (E, A) => {
    let suite = name => "suite: " + name;
    return {
      suite: suite
    };
  };
  let M = {
    Eq: Eq
  };
  let EQ = M.Eq(IntEq)(A);
  return {
    IntEq: IntEq,
    M: M,
    EQ: EQ
  };
}

let ArbitraryInt = {};

let JsQuickCheck = {};

let MochaTest = {};

function eq(a, b) {
  return a === b;
}

let IntEq = {
  eq: eq
};

function Eq(E, A) {
  let suite = name => "suite: " + name;
  return {
    suite: suite
  };
}

let M = {
  Eq: Eq
};

let EQ = M.Eq(IntEq)(ArbitraryInt);

let TestInt = {
  IntEq: IntEq,
  M: M,
  EQ: EQ
};

console.log(EQ.suite);

export {
  Interface,
  Make,
  IntWithTest,
  ArbitraryInt,
  JsQuickCheck,
  MochaTest,
  TestInt,
}
/* EQ Not a pure module */

Thank you for filing! Check list:

• Is it a bug? Usage questions should often be asked in the forum instead.
• Concise, focused, friendly issue title & description.
• A minimal, reproducible example.
• OS and browser versions, if relevant.
• Is it already fixed in master? Instructions

[cristianoc]

Here's a small example:

module Make = (T: {}, Q: {}) => {
  module Eq = (E: {}, A: {}) => {}
}

module M = Make({}, {})

module EQ = M.Eq({}, {})

produces

function Make(T, Q) {
  let Eq = (E, A) => ({});
  return {
    Eq: Eq
  };
}

function Eq(E, A) {
  return {};
}

let M = {
  Eq: Eq
};

let EQ = M.Eq({})({});

Seems like a certain level of nesting is required to observe this.

[dsiu]

@cristianoc : is this issue hard to fix? it was working on v12-alpha.3 and before so the bug was introduced recently. thanks a lot.

[cristianoc]

Perhaps one could always emit functors as functions taking one argument at a time, unless there are some issue that could come with that.

[cristianoc]

Something like this: #7273
If it works and it is safe, one can explore further.

[cristianoc]

@dsiu could you try to install the package from CI and see if it works for you?

[dsiu]

@cristianoc sure thing. Will revert back once I tested it. Thanks!

[dsiu]

@cristianoc, I'm happy to report that #7273 fixes the problem. I ran it against my larger code base, and it only changes the module functor invocations, not any other code. I think it is good to go.

Thanks again.