#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Changes (by hvr): * owner: (none) => hvr * differential: => phab:D3927 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Changes (by hvr): * related: => #10365 Old description:

More details in ​prime:Libraries/Proposals/SemigroupMonoid

For more recent details about phase 2, see https://groups.google.com/forum/#!topic/haskell-core- libraries/PyxpE2ebS9Q

New description: More details in ​prime:Libraries/Proposals/SemigroupMonoid For more recent details about phase 2, see https://groups.google.com/forum/#!topic/haskell-core-libraries/PyxpE2ebS9Q For the previous phase1, see #10365 -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Comment (by siddhanathan): Is deprecating `Data.Semigroup.Option` within the scope of this proposal? It should now be obsolete since Semigroup is a superclass of Monoid. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Comment (by RyanGlScott): The subtext of that question is that there are eventual plans to change the `Monoid` instance for `Maybe` to be `instance Semigroup a => Monoid (Maybe a)` (i.e., to remove [http://git.haskell.org/ghc.git/blob/838a10fcad9168895b49b4709056b549f2888860... this piece] of documentation). When that happens, there really will be no substantial difference between `Option` and `Maybe`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Comment (by RyanGlScott): The SMP is already a rather backwards //in//compatible change as it is (in the sense that many libraries are going to be broken until they catch up and add `Semigroup` instances), so I don't feel too shaken up about changing a `Monoid` constraint to a `Semigroup` one on top of that. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Comment (by Herbert Valerio Riedel ): In [changeset:"10ca8018900364579123bf3912202176d338d3c6/ghc" 10ca801/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="10ca8018900364579123bf3912202176d338d3c6" Generalise constraint on `instance Monoid (Maybe a)` to Semigroup This now becomes possible due to the introduction of the Semigroup=>Monoid superclass relation (see #14191). Reviewers: ekmett, RyanGlScott, austin, bgamari Reviewed By: ekmett, RyanGlScott, bgamari Subscribers: rwbarton, thomie Differential Revision: https://phabricator.haskell.org/D3972 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14191: Implement Semigroup as a superclass of Monoid Proposal (Phase 2) -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: closed Priority: normal | Milestone: 8.4.1 Component: libraries/base | Version: 8.2.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10365 | Differential Rev(s): phab:D3927 Wiki Page: | prime:Libraries/Proposals/SemigroupMonoid| -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => closed * resolution: => fixed Comment: I believe this is now done. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14191#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler