[Nix-dev] Typing nix − funding campaign

[Danylo Hlynskyi]

That looks like a feature of gradual typing: unless you exlicitly specify
type annotations, it can infer type, be it ?, ? -> ? or more complicated.

But I'm too interested on how to specify type for `if` without introducing
local lambda (e.g., will there be special syntax for this).

2017-03-29 19:25 GMT+03:00 Mateusz Kowalczyk <fuuzetsu at fuuzetsu.co.uk>:

> On 03/28/2017 10:45 AM, Théophane Hufschmitt wrote:
> > Hi everyone,
> >
> > My internship has now started, and I'll try to post regular updates on
> > https://typing-nix.regnat.ovh/ as promised. So if you're interested,
> > just follow the rss :)
> >
> >> --
> >> Théophane Hufschmitt
> >
>
> Hi,
>
> I'm sure you've answered this ad nauseum before but I wonder how you're
> going to type sets? They are bread-and-butter in nixpkgs. Presumably
> they will be typed on their fields with the standard subtyping, like
> anonymous records.
>
> Secondly, I wonder about the motivation for the typing of `if` with
> intersections. It seems counter-intuitive to have it in the type-system.
> Why not provide an explicit union type as part of some standard library?
> I would have thought that most people expect `if` to have `Bool -> a ->
> a -> a` type. Error messages suffer because it becomes unclear whether
> the caller to `if` is expecting wrong type or the `if` is providing
> wrong type. I don't think that sort of `if` usage is common in nixpkgs
> (at least not so common to justify weird typing as opposed to just
> fixing the uses which in turn could be detected if we don't have this
> typing rule).
>
> If stuff like this is already written somewhere, let me know and I'll RTFM.
>
>
> [1]: https://typing-nix.regnat.ovh/posts/lets-type-nix.html
>
>
> --
> Mateusz K.
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>
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