AW: RE: Hi. I'm new to this mailing list and have a few questions.

Tue Aug 4 18:16:05 UTC 2020

_ already has the meaning of a type wildcard (generalized from its use as a
wildcard in patterns), so this
is consistent with its use in other type signatures. The problem I see with
your proposal is that it assumes
you know the names of the type variables in the original declaration.

On Tue, Aug 4, 2020 at 2:12 PM Anselm Schüler (conversations subemail) <
conversation at anselmschueler.com> wrote:

> And also, it’s really weird and seems like a feature that should be
> removed IMO. It kind of looks like the type variable _ is always
> in-scope, and it’s unclear if the type of the resulting function is just
> type variables without an explicit forall or if _ has a special meaning.
>
>
>
> *Anselm Schüler*
>
> *www.anselmschueler.com <http://www.anselmschueler.com>*
>
>
>
> *From: *Anselm Schüler (conversations subemail)
> <conversation at anselmschueler.com>
> *Sent: *Tuesday, August 4, 2020 20:09
> *To: *Rowan Goemans <goemansrowan at gmail.com>; ghc-devs at haskell.org
> *Subject: *RE: AW: RE: Hi. I'm new to this mailing list and have a few
> questions.
>
>
>
> True, but this makes the type less readable since id @_ :: _ -> _.
>
>
>
> *Anselm Schüler*
>
> *www.anselmschueler.com <http://www.anselmschueler.com>*
>
>
>
> *From: *Rowan Goemans <goemansrowan at gmail.com>
> *Sent: *Tuesday, August 4, 2020 19:59
> *To: *ghc-devs at haskell.org
> *Subject: *Re: AW: RE: Hi. I'm new to this mailing list and have a few
> questions.
>
>
>
> Just as a heads up. You can achieve what you want already by doing:
>
> f @_ @([String]) *:: forall a. (a, [String]) -> ([String], a**) *
>
> Best regards,
>
> Rowan Goemans
>
> On 8/4/20 7:45 PM, Anselm Schüler (conversations subemail) wrote:
>
> Thank you for the nice introduction :) !
>
> I will check out the GHC proposals site.
>
> And following Simon’s (I hope addressing with first name is OK)
> suggestion, I’m going to give an outline of the idea.
>
>
>
> The idea is to extend type application syntax to enable explicit
> assignment of types to specific type variables.
>
> For instance, say I have f :: forall a b. (a, b) -> (b, a), and I want to
> apply the type [String] to it. My only option is to do
>
> f @([String]) *:: forall b. ([String], b) -> (b, [String]) *
>
> —but what if, instead, I want a function of type forall a. (a, [String])
> -> ([String], a)?
>
> I propose the following syntax:
>
> f @{b = [String]} *:: forall a. ([String], b) -> (b, [String])*
>
> This wouldn’t break any existing programs since using record syntax here
> is already disallowed and met with an error message.
>
> A question is of course the symbol used for assignment (~, =, ::, or ->?).
>
>
>
> I hope the code shows up as a monospace font on your end. I used the IBM
> Plex Mono font, which is open-source <https://github.com/IBM/plex>.
>
>
>
> *Anselm Schüler*
>
> *wwwanselmschueler.com <http://www.anselmschueler.com>*
>
> *mail at anselmschueler.com <mail at anselmschueler.com>*
>
>
>
> *From: *Simon Peyton Jones <simonpj at microsoft.com>
> *Sent: *Tuesday, August 4, 2020 18:44
> *To: *Richard Eisenberg <rae at richarde.dev>; "Anselm Schüler
> (conversations subemail)" <conversation at anselmschueler.com>
> *Cc: *ghc-devs at haskell.org
> *Subject: *RE: Hi. I'm new to this mailing list and have a few questions.
>
>
>
> Welcome Anselm  ghc-devs is a very informal mailing list, and we welcome
> newcomers.
>
>
>
> For example, I have a feature idea in the back of my mind, which I imagine
> would be easy to implement
>
>
>
> What Richard says is right, but you should feel free to fly the kite on
> this list if you want – or on Haskell Café – to get some idea of whether
> others seem warm about the idea, before writing a full proposal.
>
>
>
> Simon
>
>
>
> *From:* ghc-devs <ghc-devs-bounces at haskell.org>
> <ghc-devs-bounces at haskell.org> *On Behalf Of *Richard Eisenberg
> *Sent:* 04 August 2020 16:05
> *To:* "Anselm Schüler (conversations subemail)"
> <conversation at anselmschuelercom> <conversation at anselmschueler.com>
> *Cc:* ghc-devs at haskell.org
> *Subject:* Re: Hi. I'm new to this mailing list and have a few questions.
>
>
>
> Hi Anselm,
>
>
>
> Welcome!
>
>
>
> A good way of getting used to a list like this one is to wait a little
> while and observe what kind of messages others send; this will give you a
> feel for how the list is used. If you're impatient, you can also check out
> the archives at https://mail.haskell.org/pipermail/ghc-devs/
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.haskell.org%2Fpipermail%2Fghc-devs%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Ce68e6131af494519061c08d83887d962%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637321503404154244&sdata=w4QIMTGeMQ35bEo4xkOn2rIj8z02iMVje4Ar9AXM22k%3D&reserved=0>
> .
>
>
>
> As for a feature request: if your feature changes the language GHC accepts
> (most do), the right place to post is at
> https://githubcom/ghc-proposals/ghc-proposals
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals&data=02%7C01%7Csimonpj%40microsoft.com%7Ce68e6131af494519061c08d83887d962%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637321503404164244&sdata=ogVVk5kRFXPc81dZ%2FiyGV9FbgQoQUtzazpFGcrAKUXA%3D&reserved=0>.
> There is a description of how to proceed on that page. Proposals submitted
> there get debated within the community and then eventually sent to a GHC
> Steering Committee for a vote on acceptance or rejection. Then, we worry
> about implementing it. If you have a suggestion that does not change the
> language GHC accepts, you can post an Issue at
> https://gitlab.haskell.org/ghc/ghc/
> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Ce68e6131af494519061c08d83887d962%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637321503404164244&sdata=tg40q%2B9%2BW5KcVzHsPx9oCP7wdw5ipdZCOOdFnzUz3mU%3D&reserved=0>
> .
>
>
>
> I hope this is helpful!
>
> Richard
>
>
>
> On Aug 4, 2020, at 8:59 AM, Anselm Schüler (conversations subemail) <
> conversation at anselmschueler.com> wrote:
>
>
>
> First of all, in general, I’m new to mailing lists (as used for
> discussions) in general, so a question about that:
>
> When subscribed to the mailing list, do you get *every* message, or are
> some discussions hidden?
>
>
>
> Second of all, I’d like to know what kinds of messages are appropriate
> here. I’m not familiar with coding compilers or anything of the like, so
> I’m somewhat afraid of offering unhelpful comments or being just woefully
> underqualified to participate here.
>
> For example, I have a feature idea in the back of my mind, which I imagine
> would be easy to implement (that might be wrong). Is it alright if I submit
> that here or should I use some other forum?
>
>
>
> Thank you in advance for the answers.
>
>
>
> *Anselm Schüler*
>
> *www.anselmschueler.com
> <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.anselmschueler.com%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Ce68e6131af494519061c08d83887d962%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637321503404164244&sdata=WJBJ3P%2BFUnTmVs9Z97DHLat9mHr6vC22l0mQ36nafGc%3D&reserved=0>*
>
> *mail at anselmschueler.com <mail at anselmschueler.com>*
>
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-- 
brandon s allbery kf8nh
allbery.b at gmail.com
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