- ghc-steering-committee

Unordered extra commas
by code＠jaro.addy.io 25 May '26

25 May '26

Dear fellow committee members, We have a proposal in the pipeline about allowing extra commas <https://github.com/ghc-proposals/ghc-proposals/pull/748> in sequences where the order does not matter. These extra commas (before the first item and/or after the last item) make code layout more consistent and reduce clutter in diffs. This is a limited version of an earlier proposal which did not make it because it sparked too much controversy. The current only allows redundant commas in uncontroversial places, which roughly lines up with the intuition that for all these places the order of the sequence items does not matter. Since there hasn't been much discussion lately on this proposal, I'm asking you to provide your opinion. There are two main points of discussion: 1. Does this proposal make the right selection of places where to allow extra commas? This proposal for example does not include commas in contexts ((...here...) => ...), or in lists. I personally think we should choose carefully to avoid the situation where we do want to allow extra commas in more places in the future, because we then either need a new extension or we need to change the meaning of this extension. 2. Which extra commas do we allow? The current proposal is to allow an extra comma at the start AND at the end of a sequence. I personally think we should be more conservative and only allow one OR the other (exclusively). Another alternative is to allow extra commas anywhere in the list, even multiple in a row. I'm looking forward to your opinions, Jaro

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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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Interpolated strings
by Simon Peyton Jones 05 May '26

05 May '26

Friends We have a proposal in the committee's inbox about interpolated strings <https://github.com/ghc-proposals/ghc-proposals/pull/570>. Very few of you have contributed to a debate about it, but it's our obligation as members of the GHC Steering Committee to give it our serious attention. I have dived into it, and emerged with - This framing of the proposal <https://github.com/ghc-proposals/ghc-proposals/pull/570#discussion_r3164039…> - This articulation of the design choices <https://github.com/ghc-proposals/ghc-proposals/pull/570#discussion_r3166956…> Now it's your turn. I suggest you respond mainly on the discussion thread of the proposal. Sebastian is our shepherd and will doubtless guide our discussion 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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GHC proposals status, March 2026
by Simon Marlow 11 Mar '26

11 Mar '26

Secretary here. I wrote a little tool (or rather, got Claude to write a little tool) to analyse the current state of GHC proposals. Repository here: https://github.com/simonmar/ghc-proposals-stats Please let me know if you spot anything wrong. Some overall stats: Current state of all proposals: -------------------------------------------------- Created 91 Waiting for shepherd recommendation 4 Committee discussion 0 Needs revision 25 Rejected 16 Accepted 55 Implemented 106 Closed 301 Dormant 10 -------------------------------------------------- Total 608 There are no proposals currently in committee discussion, but we have a few waiting for shepherd recommendation: Proposals currently in 'Waiting for shepherd recommendation' state: ---------------------------------------------------------------------- PR #700 Abstract Q 1 days PR #720 GHCi command for recompilation-aware evaluation 1 days PR #742 QualifiedStrings updates 1 days PR #570 Native string interpolation syntax 0 days Activity over the last 12 months: Proposal activity since 2025-03-11: -------------------------------------------------- Created 48 Waiting for shepherd recommendation 11 Committee discussion 6 Needs revision 7 Rejected 0 Accepted 9 Implemented 5 Closed 37 Dormant 0 -------------------------------------------------- Below I've included the verbose output from the tool, which includes the history of all PRs which had some activity over the last 12 months. Cheers Simon PR #182: Add control flow hint pragmas. · 2018-11-17 Created by AndreasPK 2025-04-16 Closed by AndreasPK (+2342 days) PR #570: Native string interpolation syntax · 2023-01-11 Created by brandonchinn178 · 2024-08-04 Waiting for shepherd recommendation by adamgundry (+571 days) · 2024-08-05 Needs revision by sgraf812 (+1 days) 2026-03-11 Waiting for shepherd recommendation by sgraf812 (+583 days) PR #621: Linear constraints proposal · 2023-11-21 Created by aspiwack · 2024-12-02 Waiting for shepherd recommendation by adamgundry (+377 days) · 2024-12-06 Needs revision by JakobBruenker (+4 days) · 2025-01-10 Waiting for shepherd recommendation by aspiwack (+35 days) · 2025-01-14 Committee discussion by JakobBruenker (+4 days) 2025-03-20 Needs revision by adamgundry (+65 days) PR #632: Amend GHC2024/GHC20xx proposals to specify introduction of new language editions · 2024-01-24 Created by adamgundry · 2024-02-15 Committee discussion by adamgundry (+22 days) · 2024-04-22 Needs revision by adamgundry (+67 days) 2025-03-11 Waiting for shepherd recommendation by adamgundry (+323 days) 2025-04-09 Committee discussion by simonmar (+29 days) 2025-05-13 Closed by adamgundry (+34 days) 2025-05-13 Accepted by adamgundry (+0 days) PR #668: Allow arbitrary identifiers as fields in `OverloadedRecordDot` and `OverloadedRecordUpdate` · 2024-07-22 Created by parsonsmatt · 2024-10-29 Committee discussion by adamgundry (+99 days) · 2024-11-23 Needs revision by adamgundry (+25 days) · 2024-12-13 Waiting for shepherd recommendation by adamgundry (+20 days) · 2025-03-10 Committee discussion by adamgundry (+87 days) 2025-05-13 Closed by adamgundry (+64 days) 2025-05-13 Accepted by adamgundry (+0 days) PR #669: Add categorization of language extensions · 2024-08-05 Created by telser · 2024-10-29 Waiting for shepherd recommendation by adamgundry (+85 days) · 2024-11-11 Needs revision by maralorn (+13 days) 2025-06-23 Committee discussion by maralorn (+224 days) 2025-08-07 Closed by maralorn (+45 days) 2025-08-07 Accepted by maralorn (+0 days) PR #672: Amendment to accepted proposal 0409, requiring the default exports to be explicit · 2024-08-25 Created by blamario · 2024-09-10 Committee discussion by adamgundry (+16 days) · 2024-09-17 Closed by adamgundry (+7 days) · 2024-09-17 Accepted by adamgundry (+0 days) 2025-06-06 Implemented by adamgundry (+262 days) PR #680: Clarify CRLF behavior in multiline strings · 2024-10-16 Created by brandonchinn178 · 2024-11-11 Waiting for shepherd recommendation by adamgundry (+26 days) · 2024-11-11 Committee discussion by sgraf812 (+0 days) · 2024-11-21 Accepted by sgraf812 (+10 days) · 2024-11-22 Closed by adamgundry (+1 days) 2025-06-06 Implemented by adamgundry (+196 days) PR #681: Updates to modifiers proposal · 2024-11-07 Created by ChickenProp 2025-09-09 Waiting for shepherd recommendation by adamgundry (+306 days) 2025-09-12 Needs revision by simonpj (+3 days) 2025-10-20 Waiting for shepherd recommendation by adamgundry (+38 days) 2025-11-25 Committee discussion by adamgundry (+36 days) 2025-12-02 Accepted by Tritlo (+7 days) 2025-12-02 Closed by Tritlo (+0 days) PR #682: Explicit Level Imports · 2024-11-15 Created by mpickering · 2024-12-02 Waiting for shepherd recommendation by adamgundry (+17 days) · 2024-12-09 Needs revision by aspiwack (+7 days) · 2024-12-20 Waiting for shepherd recommendation by adamgundry (+11 days) · 2025-01-09 Committee discussion by aspiwack (+20 days) · 2025-03-06 Accepted by aspiwack (+56 days) · 2025-03-07 Closed by adamgundry (+1 days) 2025-05-13 Implemented by adamgundry (+67 days) PR #684: ForUnique Quantifier · 2024-11-28 Created by VitWW 2025-07-24 Closed by VitWW (+238 days) PR #686: Fix spec for string gaps in multiline strings · 2025-02-23 Created by brandonchinn178 · 2025-03-04 Waiting for shepherd recommendation by adamgundry (+9 days) · 2025-03-06 Committee discussion by maralorn (+2 days) 2025-04-05 Accepted by maralorn (+30 days) 2025-04-05 Closed by maralorn (+0 days) 2025-06-06 Implemented by adamgundry (+62 days) PR #687: Add proposal for amending monad of no return · 2025-02-26 Created by L0neGamer 2025-04-08 Waiting for shepherd recommendation by adamgundry (+41 days) 2025-04-19 Needs revision by adamgundry (+11 days) 2025-09-11 Closed by L0neGamer (+145 days) PR #688: Add implementation plan for #581 Namespace-specified imports 2025-03-21 Created by int-index 2025-03-22 Closed by adamgundry (+1 days) PR #689: Permutation import syntax 2025-04-01 Created by phadej PR #690: Extending Constraint Syntax to Include Disequality Constraints 2025-04-08 Created by submarinez 2025-04-08 Closed by submarinez (+0 days) PR #691: Introduce a new XLowLevelHaskell meta extension. 2025-04-16 Created by AndreasPK PR #692: Impact analysis for #581 Namespace-specified imports 2025-04-19 Created by int-index 2025-05-13 Closed by adamgundry (+24 days) PR #693: Fix typo 2025-04-20 Created by TeofilC 2025-04-21 Closed by adamgundry (+1 days) PR #695: NamedDefaults: clarify interactions 2025-04-21 Created by sheaf PR #696: Splitting out stable subsets from `template-haskell` (`template-haskell-lift` and `template-haskell-quasiquote`) 2025-04-25 Created by TeofilC 2025-06-16 Waiting for shepherd recommendation by adamgundry (+52 days) 2025-06-23 Committee discussion by sgraf812 (+7 days) 2025-07-14 Accepted by sgraf812 (+21 days) 2025-07-27 Closed by sgraf812 (+13 days) PR #697: Fix non-Nix build 2025-05-02 Created by brandonchinn178 2025-05-02 Closed by adamgundry (+0 days) PR #698: QualifiedLiterals 2025-05-07 Created by brandonchinn178 2025-07-17 Waiting for shepherd recommendation by adamgundry (+71 days) 2025-07-29 Needs revision by erikd (+12 days) 2025-08-20 Committee discussion by erikd (+22 days) 2025-09-09 Closed by brandonchinn178 (+20 days) PR #700: Abstract Q 2025-05-24 Created by TeofilC 2026-03-10 Waiting for shepherd recommendation by simonmar (+290 days) PR #701: 581: Wildcard specification 2025-06-02 Created by int-index 2025-10-28 Closed by adamgundry (+148 days) PR #705: Explicit Level Imports: refine specification for exports 2025-07-17 Created by mpickering 2025-08-07 Closed by adamgundry (+21 days) 2025-08-07 Accepted by adamgundry (+0 days) 2025-08-07 Implemented by adamgundry (+0 days) PR #707: DRAFT: Shared class methods 2025-07-21 Created by L0neGamer 2025-07-28 Closed by L0neGamer (+7 days) PR #708: DRAFT: Deriving superclasses 2025-07-21 Created by L0neGamer 2025-07-28 Closed by L0neGamer (+7 days) PR #709: ForScoped Quantifier 2025-07-24 Created by VitWW PR #710: Local Quantifiers 2025-07-24 Created by VitWW PR #711: NotProposal: Updated Proposal process 2025-08-05 Created by VitWW 2025-08-05 Closed by VitWW (+0 days) PR #712: Fix: Updated Proposal process 2025-08-05 Created by VitWW 2025-09-09 Closed by adamgundry (+35 days) PR #713: Fix documentation build on nix 2025-08-05 Created by mpickering 2025-08-07 Closed by adamgundry (+2 days) PR #715: Protected Pragma 2025-08-12 Created by Oleksandr-Zhabenko PR #716: Fix: Repair links in 0586 Split WUnused-imports 2025-08-20 Created by VitWW 2025-08-20 Closed by adamgundry (+0 days) PR #717: Fix: Repair format in 522 Or patterns 2025-08-25 Created by VitWW 2025-08-27 Closed by adamgundry (+2 days) PR #718: Fix: Repair format in 76 Numeric Underscores 2025-09-01 Created by VitWW 2025-09-01 Closed by adamgundry (+0 days) PR #719: Fix: Repair format in 111 Linear Types 2025-09-03 Created by VitWW 2025-09-04 Closed by adamgundry (+1 days) PR #720: GHCi command for recompilation-aware evaluation 2025-09-04 Created by alexfmpe 2026-03-10 Waiting for shepherd recommendation by simonmar (+187 days) PR #721: Fix: Repair format in 107 Source plugins 2025-09-08 Created by VitWW 2025-09-09 Closed by adamgundry (+1 days) PR #722: Clarify no whitespace allowed in QualifiedDo 2025-09-09 Created by brandonchinn178 2025-09-09 Closed by adamgundry (+0 days) PR #723: Break out proposal for QualifiedStrings 2025-09-09 Created by brandonchinn178 2025-10-14 Accepted by adamgundry (+35 days) 2025-10-14 Closed by adamgundry (+0 days) PR #724: Break out proposal for QualifiedLists 2025-09-09 Created by brandonchinn178 2025-10-14 Needs revision by adamgundry (+35 days) PR #725: Break out proposal for QualifiedNumerics 2025-09-09 Created by brandonchinn178 2025-10-14 Needs revision by adamgundry (+35 days) PR #726: Add section to README clarifying role of shepherd 2025-09-10 Created by adamgundry 2025-10-14 Closed by adamgundry (+34 days) PR #727: Fix: fix format at the table in Readme 2025-09-11 Created by VitWW 2025-09-25 Closed by adamgundry (+14 days) PR #729: New syntax for Visible ForAll 2025-09-20 Created by VitWW PR #730: Fixes to string proposals 2025-10-22 Created by brandonchinn178 2025-11-04 Closed by adamgundry (+13 days) PR #732: Simplify static forms 2025-11-19 Created by simonpj 2025-11-25 Waiting for shepherd recommendation by adamgundry (+6 days) 2025-12-03 Committee discussion by JakobBruenker (+8 days) 2025-12-18 Needs revision by JakobBruenker (+15 days) 2025-12-18 Accepted by JakobBruenker (+0 days) 2025-12-18 Closed by JakobBruenker (+0 days) PR #733: Differently typed duplicate record fields 2025-11-26 Created by brandonchinn178 PR #734: Deriving Superclasses 2025-12-08 Created by L0neGamer 2026-01-27 Closed by L0neGamer (+50 days) PR #735: Custom error messages for unsolved Wanteds 2025-12-18 Created by sheaf PR #737: Abstractly-keyed Implicit Bindings 2025-12-23 Created by shlevy PR #738: Amend #669 to categorize more language extensions 2026-01-12 Created by telser PR #740: LocalImports: Allow imports in let/where clauses 2026-01-19 Created by rashadg1030 PR #741: Scoped values 2026-01-26 Created by lortabac PR #742: QualifiedStrings updates 2026-01-31 Created by brandonchinn178 2026-03-10 Waiting for shepherd recommendation by simonmar (+38 days) PR #743: Contexts: A new construct for namespaces in Haskell 2026-03-02 Created by rashadg1030 2026-03-07 Closed by rashadg1030 (+5 days) 2026-03-07 Closed by rashadg1030 (+0 days) PR #744: Branch weight support 2026-03-03 Created by iand675 PR #745: Submodules 2026-03-07 Created by rashadg1030 PR #747: README: Update mailman URLs 2026-03-10 Created by TeofilC 2026-03-10 Closed by simonmar (+0 days)

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Assigning Shepherd: #720 GHCi command for recompilation-aware evaluation
by Simon Marlow 10 Mar '26

10 Mar '26

Alexandre Esteves submitted proposal *GHCi command for recompilation-aware evaluation #720* to the committee for review. https://github.com/ghc-proposals/ghc-proposals/pull/720 I'd like to nominate *myself *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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