Code won't compile with resi file present, but remove that and it compiles with no issues?

1

Ran into something peculiar here.

This is the gist of the code, which compiles fine in rescript playground ReScript Playground (rescript-lang.org)

My project won’t compile while the .resi file is present or the specification for remove_value_from_el_at_idx_and_update/2 is present in the .resi file.

There I tried messing around with just returning None from remove_value_from_el_at_idx_and_update/2 with the specification still present in the .resi file, and that works, but whenever I try returning a Some the compilation error pops up.

Compiles with no issues

let remove_value_from_el_at_idx_and_update: (array<remove_and_update_list_interface<'collection, 'a>>, int) => option<('a, array<'collection>)>
    = (xs, idx) => {
        let ys: array<'collection> = xs->Js.Array2.map(x => x.collection)
        None
    }

while this will cause a compilation error

let remove_value_from_el_at_idx_and_update: (array<remove_and_update_list_interface<'collection, 'a>>, int) => option<('a, array<'collection>)>
    = (xs, idx) => {
        let ys: array<'collection> = xs->Js.Array2.map(x => x.collection)
        Some((1, ys))
    }

yields the compilation error:

  The implementation C:\Users\jgood\Desktop\dev\candle-aggregation-res-v2\src\utils\CandleAggregationUtils.res
       does not match the interface src\utils\candleAggregationUtils-CandleAggregation.cmi:
       Values do not match:
         let remove_value_from_el_at_idx_and_update: (
  array<remove_and_update_list_interface<'collection, int>>,
  int,
) => option<(int, array<'collection>)>
       is not included in
         let remove_value_from_el_at_idx_and_update: (
  array<remove_and_update_list_interface<'collection, 'a>>,
  int,
) => option<('a, array<'collection>)>
       File "C:\Users\jgood\Desktop\dev\candle-aggregation-res-v2\src\utils\CandleAggregationUtils.resi", line 19, characters 1-144:
         Expected declaration
       File "C:\Users\jgood\Desktop\dev\candle-aggregation-res-v2\src\utils\CandleAggregationUtils.res", line 157, characters 5-43:
         Actual declaration

I hope I’m not missing something glaringly obvious.

2

can you come up with a repro in the playground?
All you have to do to simulate a .resi file is to wrap your code inside a module and add a signature to it.

3

https://rescript-lang.org/try?version=v10.1.2&code=LYewJgrgNgpgBAFwJ4Ad4EkB2CYCcBmAhgMbwC8cA3gFACQyacuMoAbjAPqGZgcQphCODlACWAZwQdR2PEVIAeAOTEQUWMQSiQmADRwlhAHxwKNOBcur1MTdswAuA9Y1adu6pcvM2MJwAoVNVd7UxMQFDdMBUDCfTFJZWMASiNksLgIqJjDeIkEJLSjDy8LfkEcJwSCwxMyEyCbOx1POABfalbYBCYWEHYOVkIoCE58XBBgDhgoLilRMAAPLh4+ASE-OH9W0rhCXFxCJAUffs5uXnKNkXzpWQISGGUXWyj9WuKd0pkEEst0+qZSL2HJxPYHI7PYKvexFCzUDrUUCQWBwdDAFBQJxYHAPUimKhdGA9cSEfCcADmxIC+0Ox1q+h+APCwJ0hS+FH8i3EjKWzMJuwsCFwSAFgq8AGVJjAueIANoLRYAXWSXy8bTgxCExAAFmLxRYAD5wDgZAByOhgassHXVnW6vV8HHwolwkmdEym1Sq+UKGSyINieUStVSHK23P54gA7qIELq4Nz9aVjdVKBrARbMFbxan8pQXW7fnAAHRlnyEGQyCkZkxS4Ay-yFyT6CtVzAU5Kqu3UB3MTGPaazGRcCFIObSJY0seFRnYd6Efm0yG1cOypzL+nGXmLJw-fS7gyLjLmQUOyT7HoUABS4hLAEExwAmEviMSkWX6AB+F9wCDIAAM34wKsZCKt2Z7EnAIFgASt4Ps+r7vjK3Lfr+-6KgA1AAjMBoEALTYRBuzwY+dIvqomBaggACy3BIP46H6HKcrKvoMEql8iIMPApwDBcawVJw1R3Li8hPI0ITuEedTJi8zSOM40IKX8Fh8ZsgTyVE-qstEQZwNUhSpPyAZsvphmhp8XhXJUBm+rUGSSTCLSIn2fQDEMIxjJ6Q4ToqKyXOstnbOKm4nO55yrDZwm3D8ciPFCTRvDJVmCvuXwmbpoL6GFTkKUUa6oXAip7tgzLWhYMZxgmpLkhwVIIJ+xV8smuZwPWMrAII-KngapQOoepl6bk4J0olUmYHCFBVfGepdYQJbqf46nOq67rjJMNySOkvV9YKxodf4TZrcWbaYNWXYnhVe27ANTh5dpFDzSW0XLSwlbnR2xE3QaDpIOIG4zg9sIEty+FGKRiHAIQKBchkiwllp9jfT9kE9NFYCA2NwM6LJ-ZQIOMx3KOdJ+Us-j-TuB7pNdqMWIdx1FvoGNdrTe22nTXjGlm5AmDzbO7IinOLAL7Si9zlrmpa10dB0QA

4

Okay, I did miss something glaringly obvious, but weird that the implementation of remove_value_from_el_at_idx_and_update didn’t cause this to fail to compile when not using a .resi file.

This

type remove_and_update_list_interface<'collection, 'a> = {
    collection: 'collection,
    remove: ('collection => option<('a, list<'a>)>) => option<('a, list<'a>)>,
    update: list<'a> => 'collection
}

Needed to be updated to this

type remove_and_update_list_interface<'collection, 'a> = {
    collection: 'collection,
    remove: (list<'a> => option<('a, list<'a>)>) => option<('a, list<'a>)>,
    update: list<'a> => 'collection
}

Because

let remove_value_from_el_at_idx_and_update: (array<remove_and_update_list_interface<'collection, 'a>>, int) => option<('a, array<'collection>)>
    = (xs, idx) =>
        switch Utils.safe_get(xs, idx) {
            | Some(mda) => {
                let x: option<('a, array<'collection>)> = switch mda.remove(Utils.remove_first_from_list) { // remove_first_from_list: list<'a> => option<('a, list<'a>)>, would've suspected a compiler error from this with the first type spec of remove_and_update_list_interface
                    | Some((first, remaining)) => {
                        let x: 'collection = mda.update(remaining)
                        let ys: array<'collection> = xs->Js.Array2.map(x => x.collection)
                        let updated: array<'collection> = Utils.replace_el_in_array_at_idx(ys, idx, x) 
                        Some((first, updated))
                    }
                    | None => None
                }

                x
            }
            | None => None
        }
5

the compilation did not fail because 'collection got inferred as list<'a>

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