[GHC] #9724: reexport IsList class from a trustworthy module
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: ekmett Type: feature request | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- ==== Motivation GHC's Safe Haskell extension relies to a large extent on inferring safety of modules automatically. As a concrete example, [[http://hackage.haskell.org/package/data-default|data-default]] used to be inferred safe. This is no longer the case, because [[http://hackage.haskell.org/package/dlist-0.7.1|dlist-0.7.1]] added an {{{IsList}}} instance for difference lists. The only way to do that currently is to import the relevant parts of {{{GHC.Exts}}}, and that module is not safe. Of course the resulting non-safety of the {{{Data.DList}}} module can be fixed by adding a {{{TrustWorthy}}} pragma to the module and trusting the {{{dlist}}} package. But that is unsatisfactory, because there is nothing unsafe about providing an instance for the {{{IsList}}} class. This issue is bound to pop up in other packages as well. ==== Proposed Solution (this is one of many possibilities) Add a {{{GHC.Exts.Safe}}} module that is marked {{{TrustWorthy}}} and reexports the {{{IsList}}} class, and possibly other things from {{{GHC.Exts}}} that are safe to use. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: ekmett Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.3 Component: Core | Keywords: Libraries | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by goldfire): * cc: eir@… (added) Comment: I agree that this deserves some attention. I always feel dirty importing `GHC.Exts`, and the non-dirty things from there should have other places to be pulled from. I'm specifically thinking of `Constraint`, but I'm sure there are things other than just `IsList` and `Constraint` that should find new homes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: ekmett Type: feature request | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by oerjan): * cc: oerjan (added) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.8.3 Resolution: | Keywords: SafeHaskell Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by thomie): * cc: dterei, ekmett (added) * keywords: => SafeHaskell -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.8.3 Resolution: | Keywords: SafeHaskell Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by kostmo): This issue also seems to block [https://github.com/Daniel-Diaz/sorted- list/pull/5 marking the `sorted-list` package as safe]. Does the `IsList` class (and its instances) depend on any unsafe functionality? If not, could a new marked-`Safe` module named `GHC.Exts.List` be created so that people can safely import this subset? `GHC.Exts.List` could then be re- exported from `GHC.Exts` for backwards-compatibility. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9724: reexport IsList class from a trustworthy module -------------------------------------+------------------------------------- Reporter: int-e | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.8.3 Resolution: | Keywords: SafeHaskell Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by kostmo): * cc: kostmo (added) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9724#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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