#10820: Provide a way to detect what extensions are enabled via TH -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by goldfire): * milestone: => 7.12.1 Comment: I've wanted this, too. It should be able to happen by 7.12. But, what data type to use for the extensions? Would it work to have `template-haskell` depend on `Cabal` to pull the extension type from there? My guess: no. Would it work to have `template-haskell` depend on `ghc` and pull the type from `DynFlags`? My guess: yes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10820#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10820: Provide a way to detect what extensions are enabled via TH -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by goldfire): Bah. Of course you're right. And I don't think it's a great idea to depend on `Cabal` because that package can be upgraded independently of GHC. Correct me if this wouldn't cause pain. I guess we could have Yet Another List Of Extensions. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10820#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10820: Provide a way to detect what extensions are enabled via TH -------------------------------------+------------------------------------- Reporter: spinda | Owner: spinda Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: th/T18020.hs Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1200 -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"c1e25536d67fba33ad6ddae5556115340d99000a/ghc" c1e2553/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="c1e25536d67fba33ad6ddae5556115340d99000a" Expose enabled language extensions to TH This exposes `template-haskell` functions for querying the language extensions which are enabled when compiling a module, - an `isExtEnabled` function to check whether an extension is enabled - an `extsEnabled` function to obtain a full list of enabled extensions To avoid code duplication this adds a `GHC.LanguageExtensions` module to `ghc-boot` and moves `DynFlags.ExtensionFlag` into it. A happy consequence of this is that the ungainly `DynFlags` lost around 500 lines. Moreover, flags corresponding to language extensions are now clearly distinguished from other flags due to the `LangExt.*` prefix. Updates haddock submodule. This fixes #10820. Test Plan: validate Reviewers: austin, spinda, hvr, goldfire, alanz Reviewed By: goldfire Subscribers: mpickering, RyanGlScott, hvr, simonpj, thomie Differential Revision: https://phabricator.haskell.org/D1200 GHC Trac Issues: #10820 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10820#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10820: Provide a way to detect what extensions are enabled via TH -------------------------------------+------------------------------------- Reporter: spinda | Owner: spinda Type: feature request | Status: closed Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.10.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: th/T18020.hs Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1200 Wiki Page: | -------------------------------------+------------------------------------- Description changed by bgamari: Old description:

This would be helpful for providing users with intuitive/explanatory error messages if generated code relies on an extension that the user may not have enabled.

Sample specification, to get things started:

{{{ enabledExts :: Q [Extension] isExtEnabled :: Extension -> Q Bool data Extension = LiberalTypeSynonyms | RankNTypes | ... -- mirroring ExtensionFlag in DynFlags }}}

See #10819 for an example case where this could be of use.

New description: This would be helpful for providing users with intuitive/explanatory error messages if generated code relies on an extension that the user may not have enabled. Sample specification, to get things started: {{{#!hs enabledExts :: Q [Extension] isExtEnabled :: Extension -> Q Bool data Extension = LiberalTypeSynonyms | RankNTypes | ... -- mirroring ExtensionFlag in DynFlags }}} See #10819 for an example case where this could be of use. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10820#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler