Re: [ghc-steering-committee] Amend or patterns (#522) to use p1 ; p2 (#609)

8 Sep 2023

      No objections from me. I tend not to pay too much attention to such 
syntactic niceties, but as the authors have gone to the trouble of 
surveying the community and implementing the proposal I see no reason 
not to accept their suggested syntax.

I did notice that the PR drops Ömer's name from the authors list for 
#522, I'm not sure if that was intentional?

Adam

On 08/09/2023 18:47, Vladislav Zavialov wrote:
...
In favor
On Fri, Sep 8, 2023 at 6:36 PM Simon Peyton Jones 
mailto:simon.peytonjones@gmail.com> wrote:
I don't have a strong opinion here.   The authors have done a pretty
    diligent job of exploring syntactic alternatives, and seeking
    feedback from the community.  I'm quite content to accept this
    proposal.  (We have already accepted the base or-pattern proposal,
    so that's not our subject for debate.)
Simon
On Fri, 8 Sept 2023 at 03:57, Chris Dornan mailto:chris@chrisdornan.com> wrote:
Proposal: Amend or patterns (#522) to use p1 ; p2 (#609)
        Author: Sebastian Graf, David Knothe
        Rendered proposal:
        https://github.com/ghc-proposals/ghc-proposals/blob/eb4b67c29282520b2c5c6a49... https://github.com/ghc-proposals/ghc-proposals/blob/eb4b67c29282520b2c5c6a49...
        Discussion:
        https://github.com/ghc-proposals/ghc-proposals/pull/609
        https://github.com/ghc-proposals/ghc-proposals/pull/609
        Recommendation: Acceptance
## Summary
This proposal refines the syntax of an already accpted proposal
        (#522) for writing or patterns.
The syntax of the old proposal,
```haskell
        stringOfT :: T -> Maybe String
        stringOfT (T1 s) = Just s
        stringOfT (one of T2{}, T3{}) = Nothing
        ```
is replaced with
```haskell
        stringOfT :: T -> Maybe String
        stringOfT (T1 s) = Just s
        stringOfT (T2{}; T3{}) = Nothing
        ```
or indeed
```haskell
        stringOfT :: T -> Maybe String
        stringOfT x = case x of
        T1 s -> Just s
        T2{}
        T3{} -> Nothing
        ```
(Beacuse the '(' ... ')' are optional here, we can remove them
        and naturally exploit layout.)
The authors have conducted polls to see what folks preferred,
        landing on this proposal. The
        adjustments to the Haskell grammar are really quite minimal
        requiring one extra production.
## Recommendation
The proposal is nondiruptive and as a whole addresses an
        important practical topic. I recommend
        that we accept it
-- 
Adam Gundry, Haskell Consultant
Well-Typed LLP, https://www.well-typed.com/

Registered in England & Wales, OC335890
27 Old Gloucester Street, London WC1N 3AX, England