April 2026 - ghc-steering-committee

Please review #678: Amendment to ImportShadowing
by Adam Gundry 11 Jun '26

11 Jun '26

Dear Committee, Gergő Érdi proposes to amend his import shadowing proposal #652 to clarify the behaviour of module re-exports: https://github.com/ghc-proposals/ghc-proposals/pull/678 I'd like to nominate Erik de Castro Lopo as the shepherd, as he shepherded the original proposal. Please guide us to a conclusion as outlined in https://github.com/ghc-proposals/ghc-proposals#committee-process Cheers, Adam -- 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

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#570: Native string interpolation syntax
by Sebastian Graf 16 May '26

16 May '26

Dear committee, In #570 <https://github.com/ghc-proposals/ghc-proposals/pull/570>, Brandon Chinn proposes adding native string interpolation syntax to GHC, along the lines of s"a ${x + 1} b", catching up with and even exceeding similar features in popular programming languages. The desugaring of s"a ${x + 1} b" is: ``` Data.String.Interpolate.Experimental.interpolateString ( \convert raw append empty -> raw "a " `append` convert (x + 1) `append` raw " b" `append` empty ) :: String ``` where the following definitions are added to ghc-experimental: ``` class Interpolate a where interpolate :: a -> String type SimpleStringInterpolator s = ( forall ss. (forall a. Interpolate a => a -> s) -> (s -> s) -> (s -> ss -> ss) -> ss -> ss ) -> s interpolateString :: (IsString s, Monoid s) => SimpleStringInterpolator s interpolateString f = mconcat $ f (fromString . interpolate) id (:) [] ``` With -XQualifiedStrings, the string interpolation function may be rebound as well: ``` SQL.s"select * from users where name = ${Text.toUpper name} and age = ${age}" -- desugars to SQL.interpolateString $ \convert raw append empty -> raw "select * from users where name = " `append` convert (Text.toUpper name) `append` raw " and age = " `append` convert age `append` empty ``` I think this is an important proposal and I would emphatically accept one form or anothter. It is a useful feature with a long history of continued refinement by Brandon. I'm torn however on the particular expansion to a second-order function. See this thread: https://github.com/ghc-proposals/ghc-proposals/pull/570/changes#r3040723908 I would sacrifice generality and implement a simpler expansion instead, such as ``` mconcat [ fromString "a " , interpolate (x + 1) , fromString "b" ] :: String ``` So I abstain from voting for the particular version of the proposal. Cheers, Sebastian

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The role of the shepherd
by Simon Peyton Jones 12 May '26

12 May '26

Friends I have realised, rather belatedly, that we don't actually have any written guidance for shepherds of GHC proposals, so we all have to make it up as we go along. Perhaps it'd be helpful to have some. Here's a start. The shepherd does these things: - Makes a recommendation to the committee for whether to accept, reject, or send back for revision, within a week of being appointed. - Actively guide the committee's discussion. - Maintain a list of votes on this spreadsheet <https://docs.google.com/spreadsheets/d/1e6GdwHmAjeDEUhTvP-b18MDkpTfH3SMHhFu…> . - Actively facilitate the committee discussion, guiding us towards a decision, within the published time frame of 4-5 weeks. - Summarise the committee's thinking for the author's benefit, and work with the author on next steps -- this may often take the form of revisions to the proposal. - - Remind members (by name, not just general exhortation) who are silent that they are highly encouraged to contribute. - If the discussion does not converge within 4-5 weeks, take action to consult the chair, vice-chair, or secretary to decide what to do. It's much more than "make a recommendation and wait". Being a member of the GHC Steering Committee is a real service to the community. But of course we all have day jobs, and so not everything happens as we hope. Any thoughts? Simon

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Assigning Shepherd: #700 Abstract Q
by Simon Marlow 04 May '26

04 May '26

Teo Camarasu submitted proposal *#700: Abstract Q* to the committee for review. https://github.com/ghc-proposals/ghc-proposals/pull/700 I'd like to nominate *Sebastian Graf *as the shepherd. Please guide us to a conclusion as outlined in https://github.com/ghc-proposals/ghc-proposals/blob/master/README.rst#commi…. If possible, please aim to make a recommendation by *24 March 2026*. Cheers Simon

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Assigning Shepherd: #748 Unordered redundant commas
by Simon Marlow 30 Apr '26

30 Apr '26

VitWW submitted proposal *#748 Unordered redundant commas* to the committee for review https://github.com/ghc-proposals/ghc-proposals/pull/748 I'd like to nominate *Jaro Reinders* as the shepherd. Please guide us to a conclusion as outlined in https://github.com/ghc-proposals/ghc-proposals/blob/master/README.rst#commi…. If possible, please aim to make a recommendation by *22 April 2026*. Cheers Simon

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Assigning Shepherd: #742 QualifiedStrings updates
by Simon Marlow 21 Apr '26

21 Apr '26

Brandon Chinn submitted proposal *#742 QualifiedStrings updates *to the committee for review. https://github.com/ghc-proposals/ghc-proposals/pull/742 I'd like to nominate *Rodrigo Mesquita *as the shepherd. Please guide us to a conclusion as outlined in https://github.com/ghc-proposals/ghc-proposals/blob/master/README.rst#commi…. If possible, please aim to make a recommendation by *24 March 2026*. Cheers Simon

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Discussion: #673 Update jsem proposal to address problems discovered in GHC #25087
by Simon Marlow 14 Apr '26

14 Apr '26

wz1000 submitted proposal #673: Update jsem proposal to address problems discovered in GHC #25087 <https://github.com/ghc-proposals/ghc-proposals/pull/673> The proposal is an update to the `-jsem` mechanism for sharing compute resources between Cabal/stack and GHC, which was previously accepted as proposal #540. In summary #673 fixes an issue with #540: the specified implementation had a potential for runtime crashes due to dependence on the representation of a runtime shared data structure (the system semaphore). The technical fix is to provide a protocol layer to abstract away from the representation. This is an implementation detail though; the problem with the proposal is that it *overspecified the implementation*. The fix is to avoid doing that, and introduce a mechanism for versioning the protocol to allow for future changes. As shepherd I'm recommending acceptance.

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