<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi Bryan,<div class=""><br class=""></div><div class="">First off, sorry if my first response was a bit snippy -- it wasn't meant to be, and I appreciate the angle you're taking in your question. I just didn't understand it!</div><div class=""><br class=""></div><div class="">This second question is easier to answer. I say "forall a arrow a arrow Int".</div><div class=""><br class=""></div><div class="">But I still think there may be a deeper question here left unanswered...</div><div class=""><br class=""></div><div class="">Richard<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Nov 18, 2020, at 6:11 AM, Bryan Richter <<a href="mailto:b@chreekat.net" class="">b@chreekat.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div dir="auto" class="">Yeah, sorry, I think I'm in a little over my head here. :) But I think I can ask a more answerable question now: how does one pronounce "forall a -> a -> Int"?</div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Den tis 17 nov. 2020 16:27Richard Eisenberg <<a href="mailto:rae@richarde.dev" target="_blank" class="">rae@richarde.dev</a>> skrev:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Bryan,<br class="">
<br class="">
I don't think I understand what you're getting at here. The difference between `forall b .` and `forall b ->` is only that the choice of b must be made explicit. Importantly, a function of type e.g. `forall b -> b -> b` can *not* pattern-match on the choice of type; it can bind a variable that will be aliased to b, but it cannot pattern-match (say, against Int). Given this, can you describe how `forall b ->` violates your intuition for the keyword "forall"?<br class="">
<br class="">
Thanks!<br class="">
Richard<br class="">
<br class="">
> On Nov 17, 2020, at 1:47 AM, Bryan Richter <<a href="mailto:b@chreekat.net" rel="noreferrer" target="_blank" class="">b@chreekat.net</a>> wrote:<br class="">
> <br class="">
> Dear forall ghc-devs. ghc-devs,<br class="">
> <br class="">
> As I read through the "Visible 'forall' in types of terms"<br class="">
> proposal[1], I stumbled over something that isn't relevant to the<br class="">
> proposal itself, so I thought I would bring it here.<br class="">
> <br class="">
> Given<br class="">
> <br class="">
> f :: forall a. a -> a (1)<br class="">
> <br class="">
> I intuitively understand the 'forall' in (1) to represent the phrase<br class="">
> "for all". I would read (1) as "For all objects a in Hask, f is some<br class="">
> relation from a to a."<br class="">
> <br class="">
> After reading the proposal, I think my intuition may be wrong, since I<br class="">
> discovered `forall a ->`. This means something similar to, but<br class="">
> practically different from, `forall a.`. Thus it seems like 'forall'<br class="">
> is now simply used as a sigil to represent "here is where some special<br class="">
> parameter goes". It could as well be an emoji.<br class="">
> <br class="">
> What's more, the practical difference between the two forms is *only*<br class="">
> distinguished by ` ->` versus `.`. That's putting quite a lot of<br class="">
> meaning into a rather small number of pixels, and further reduces any<br class="">
> original connection to meaning that 'forall' might have had.<br class="">
> <br class="">
> I won't object to #281 based only on existing syntax, but I *do*<br class="">
> object to the existing syntax. :) Is this a hopeless situation, or is<br class="">
> there any possibility of bringing back meaning to the syntax of<br class="">
> "dependent quantifiers"?<br class="">
> <br class="">
> -Bryan<br class="">
> <br class="">
> [1]: <a href="https://github.com/ghc-proposals/ghc-proposals/pull/281" rel="noreferrer noreferrer" target="_blank" class="">https://github.com/ghc-proposals/ghc-proposals/pull/281</a><br class="">
> _______________________________________________<br class="">
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</blockquote></div>
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