Ensuring that bind and bindW pass the correct params through rather t…

[feydan]

…han get rewritten by the function passed in

Fixes https://github.com/gcanti/fp-ts/issues/1583

The following code improperly raises a type error:

  const func1 = (i: {arg1: string}) => TE.right('result1')
  const func2 = (i: {arg2: string, result1: string}) => TE.right('result2')

  pipe(
    TE.right({arg1: 'arg1', arg2: 'arg2'}),
    TE.bindW('result1', func1),
    TE.bindW('result2', func2),
  )

This is because this line improperly rewrites the parameter list that gets passed into the next function in the pipe TE.bindW('result1', func1),

This MR changes the passed in function to have its own generic that extends the param list. This allows the params to flow through as expected.

edit: formatting

[feydan]

Unfortunately, this seems to cause another issue:

// proper param passthrough
    const c = (p: { a: number }) => _.right<string, number>(p.a)
    const d = (p: { b: string }) => _.right<string, string>(p.b)
    U.deepStrictEqual(
      await pipe(
        _.right<string, number>(1),
        _.bindTo('a'),
        _.bind('b', () => _.right('b')),
        _.bind('c', c),
        _.bind('d', d),
        _.bind('e', _.fromIOK(i => () => 'io')) // Type 'A2' is not assignable to type 'A2'. Two different types with this name exist, but they are unrelated.
      )(),
      E.right({ a: 1, b: 'b', c: 1, d: 'b', e: 'io' })
    )

Looking into alternatives.

[feydan]

Unfortunately, this seems to cause another issue:

// proper param passthrough
    const c = (p: { a: number }) => _.right<string, number>(p.a)
    const d = (p: { b: string }) => _.right<string, string>(p.b)
    U.deepStrictEqual(
      await pipe(
        _.right<string, number>(1),
        _.bindTo('a'),
        _.bind('b', () => _.right('b')),
        _.bind('c', c),
        _.bind('d', d),
        _.bind('e', _.fromIOK(i => () => 'io')) // Type 'A2' is not assignable to type 'A2'. Two different types with this name exist, but they are unrelated.
      )(),
      E.right({ a: 1, b: 'b', c: 1, d: 'b', e: 'io' })
    )

Looking into alternatives.

I think I found a solution -- the change is committed.

[gcanti]

npm run fix-prettier should fix the CI failure

[gcanti]

Thank you @feydan

[thewilkybarkid]

I'm trying out 2.13.0-rc.4, and this change seems to cause a type of failure in an existing (working) project. I'm seeing if I can create a reproducible failure/fix.

[thewilkybarkid]

So the failure is related to inference and ts-pattern in https://github.com/PREreview/prereview.org/blob/b9f3de1477e2904fcbeee2ed70cc7e1aa7a24a6e/src/infrastructure.ts#L145-L153

Seems like the union type causes the exhaustiveness check to fail.

I can extract a typed function which gets around the issue, but this wasn't possible before this change. 😃

[thewilkybarkid]

Reproduction with ts-pattern

I'll open a ts-pattern issue due to the problem there with generics (edit: https://github.com/gvergnaud/ts-pattern/issues/111).

[gcanti]

Thank you @thewilkybarkid, I'll revert this change as is causing a regression (might be rescheduled for 2.14)