[ghc-steering-committee] #475: New tuple and list syntax, rec: accept

[Simon Peyton Jones]

> Personally I’d drop TupleN/ConstraintN and accept the rest of the
proposal, but I’d love to hear more opinions. Let me know what you think!

I agree.

I'm also not sure if we should have `Tuple` and `Constraints` or `Tuple`
and `CTuple`.  I lean to the latter.

On Sun, 30 Jan 2022 at 10:24, Vladislav Zavialov (int-index) <
vlad.z.4096 at gmail.com> wrote:

> Dear Committee,
>
> Richard has proposed #475 "New tuple and list syntax”. Read it here:
>
>
> https://github.com/goldfirere/ghc-proposals/blob/tuple-syntax/proposals/0000-tuple-syntax.rst
>
> Here’s some background:
> Earlier we accepted #281 "Visible 'forall' in types of terms”, which
> introduced, among other things, the -X(No)ListTupleTypeSyntax extension.
> During implementation, I discovered that this part of the proposal required
> further design considerations. Richard has kindly agreed to take a stab at
> this problem, and #475 is the result.
>
> Short summary of the proposal:
> * Introduce Tuple2, Tuple3, Tuple4, and so on, as alternative ways to
> write the types of tuples.
> * Introduce List as the alternative way to write the type of a list.
> * Do the same for unboxed tuples, unboxed sums, and constraint tuples.
>
> This is the core part of the proposal, for which I strongly urge
> acceptance.
>
> There are also other minor additions:
> * Rename -XListTupleTypeSyntax to -XListTuplePuns.
> * Introduce Tuple [a, b, c] as a more convenient way of writing Tuple3 a b
> c (likewise for n/=3)
> * Introduce Constraints [a, b, c] as a more convenient way of writing
> CTuple3 a b c (likewise for n/=3)
> * Introduce TupleN a b c as another more convenient way of writing Tuple3
> a b c (likewise for n/=3)
> * Introduce CTupleN a b c as another more convenient way of writing
> CTuple3 a b c (likewise for n/=3)
>
> I foresee that if we don’t include Tuple/Constraints, users will end up
> defining their own, with different libraries exporting conflicting
> definitions. TupleN/ConstraintN, on the other hand, seem weakly motivated.
>
> Personally I’d drop TupleN/ConstraintN and accept the rest of the
> proposal, but I’d love to hear more opinions. Let me know what you think!
>
> - Vlad
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