| Once we treat kind and type variables identically, I want to just rely on
| ScopedSort. That is, GHC should infer the order [j,a,k,b]. While I
| understand the aesthetic appeal of moving k before a, I think it's simpler
| and more uniform just to use ScopedSort. No exceptions!
I agree. And then we can dispose entirely of the FreeKiTyVars stuff in RnTypes.
Vlad: doing so would fit very neatly into
https://gitlab.haskell.org/ghc/ghc/merge_requests/361
Simon
| -----Original Message-----
| From: ghc-devs On Behalf Of Richard
| Eisenberg
| Sent: 14 February 2019 19:04
| To: Ryan Scott
| Cc: ghc-devs@haskell.org
| Subject: Re: scopedSort and kind variable left-biasing
|
|
|
| > On Feb 14, 2019, at 10:34 AM, Ryan Scott wrote:
| >
| > the answer [j,a,k,b]! Strictly speaking, this answer meets the
| specification of ScopedSort,
|
| I wish to point out that the specification of ScopedSort is very tight: it
| says exactly what we should get, given an input. This is important, because
| the behavior of ScopedSort is user-visible and must be stable. Another way
| of saying this: if we got [j,k,a,b], that would be wrong. Arguably, GHC's
| behavior w.r.t. type and kind variables is wrong because of its habit of
| putting kind variables first.
|
| Once we treat kind and type variables identically, I want to just rely on
| ScopedSort. That is, GHC should infer the order [j,a,k,b]. While I
| understand the aesthetic appeal of moving k before a, I think it's simpler
| and more uniform just to use ScopedSort. No exceptions!
|
| Richard
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