I’m on the fence:
But the spec is distressingly ad-hoc. Magical behaviour if
So I lean to rejection. Unless some stronger motivations emerge.
Simon
From: ghc-steering-committee <ghc-steering-committee-bounces@haskell.org>
On Behalf Of Richard Eisenberg
Sent: 06 May 2018 20:27
To: Iavor Diatchki <iavor.diatchki@gmail.com>
Cc: ghc-steering-committee@haskell.org; Joachim Breitner <mail@joachim-breitner.de>
Subject: Re: [ghc-steering-committee] TypeApplications for Overloaded Literals (#129), Recommendation: accept
I'm also unconvinced about this proposal. It's hard to specify, requiring that Prelude.fromInteger be magical. Note that if someone defined a separate Num class (under -XNoImplicitPrelude -XRebindableSyntax) that's fully equivalent to Prelude.Num,
it wouldn't work. Also, Joachim's point about `:t 5` is a poor motivation: `:t` does not give you helpful information w.r.t. type applications. You need `:t +v`. With -fprint-explicit-foralls,
λ> :t +v 5
5 :: forall {p}. Num p => p
The appearance of the braces in the output means that 5 is not available for visible type application (the variable p is *inferred*). So if there's any unexpected behavior in the current implementation, that's due to ill-informed expectations,
not misbehavior.
In the end, I would prefer to reject this proposal in favor of Joachim's casual proposal here: https://mail.haskell.org/pipermail/ghc-steering-committee/2018-May/000541.html
(and expanded upon by my subsequent post).
Richard