1. 08 Mar, 2018 2 commits
  2. 02 Mar, 2018 1 commit
  3. 18 Feb, 2018 1 commit
    • Matthías Páll Gissurarson's avatar
      Add valid refinement substitution suggestions for typed holes · 918c0b39
      Matthías Páll Gissurarson authored and Ben Gamari's avatar Ben Gamari committed
      This adds valid refinement substitution suggestions for typed holes and
      documentation thereof.
      
      Inspired by Agda's refinement facilities, this extends the typed holes
      feature to be able to search for valid refinement substitutions, which
      are substitutions that have one or more holes in them.
      
      When the flag `-frefinement-level-substitutions=n` where `n > 0` is
      passed, we also look for valid refinement substitutions, i.e.
      substitutions that are valid, but adds more holes. Consider the
      following:
      
        f :: [Integer] -> Integer
        f = _
      
      Here the valid substitutions suggested will be (with the new
      `-funclutter-valid-substitutions` flag for less verbosity set):
      
      ```
        Valid substitutions include
          f :: [Integer] -> Integer
          product :: forall (t :: * -> *).
                    Foldable t => forall a. Num a => t a -> a
          sum :: forall (t :: * -> *).
                Foldable t => forall a. Num a => t a -> a
          maximum :: forall (t :: * -> *).
                    Foldable t => forall a. Ord a => t a -> a
          minimum :: forall (t :: * -> *).
                    Foldable t => forall a. Ord a => t a -> a
          head :: forall a. [a] -> a
          (Some substitutions suppressed; use -fmax-valid-substitutions=N or
      -fno-max-valid-substitutions)
      ```
      
      When the `-frefinement-level-substitutions=1` flag is given, we
      additionally compute and report valid refinement substitutions:
      
      ```
        Valid refinement substitutions include
          foldl1 _ :: forall (t :: * -> *).
                      Foldable t => forall a. (a -> a -> a) -> t a -> a
          foldr1 _ :: forall (t :: * -> *).
                      Foldable t => forall a. (a -> a -> a) -> t a -> a
          head _ :: forall a. [a] -> a
          last _ :: forall a. [a] -> a
          error _ :: forall (a :: TYPE r).
                      GHC.Stack.Types.HasCallStack => [Char] -> a
          errorWithoutStackTrace _ :: forall (a :: TYPE r). [Char] -> a
          (Some refinement substitutions suppressed; use
      -fmax-refinement-substitutions=N or -fno-max-refinement-substitutions)
      ```
      
      Which are substitutions with holes in them. This allows e.g. beginners
      to discover the fold functions and similar.
      
      We find these refinement suggestions by considering substitutions that
      don't fit the type of the hole, but ones that would fit if given an
      additional argument. We do this by creating a new type variable with
      newOpenFlexiTyVarTy (e.g. `t_a1/m[tau:1]`), and then considering
      substitutions of the type `t_a1/m[tau:1] -> v` where `v` is the type of
      the hole. Since the simplifier is free to unify this new type variable
      with any type (and it is cloned before each check to avoid
      side-effects), we can now discover any identifiers that would fit if
      given another identifier of a suitable type. This is then generalized
      so that we can consider any number of additional arguments by setting
      the `-frefinement-level-substitutions` flag to any number, and then
      considering substitutions like e.g. `foldl _ _` with two additional
      arguments.
      
      This can e.g. help beginners discover the `fold` functions.
      This could also help more advanced users figure out which morphisms
      they can use when arrow chasing.
      Then you could write `m = _ . m2 . m3` where `m2` and `m3` are some
      morphisms, and not only get exact fits, but also help in finding
      morphisms that might get you a little bit closer to where you want to
      go in the diagram.
      
      Reviewers: bgamari
      
      Reviewed By: bgamari
      
      Subscribers: rwbarton, thomie, carter
      
      Differential Revision: https://phabricator.haskell.org/D4357
      918c0b39
  4. 05 Feb, 2018 1 commit
  5. 01 Feb, 2018 1 commit
    • takano-akio's avatar
      Implement BlockArguments (#10843) · be84823b
      takano-akio authored and Ben Gamari's avatar Ben Gamari committed
      This patch implements the BlockArguments extension, as proposed at
      https://github.com/ghc-proposals/ghc-proposals/pull/90. It also
      fixes #10855 as a side-effect.
      
      This patch adds a large number of shift-reduce conflicts to the parser.
      All of them concern the ambiguity as to where constructs like `if` and
      `let` end. Fortunately they are resolved correctly by preferring shift.
      
      The patch is based on @gibiansky's ArgumentDo implementation (D1219).
      
      Test Plan: ./validate
      
      Reviewers: goldfire, bgamari, alanz, mpickering
      
      Reviewed By: bgamari, mpickering
      
      Subscribers: Wizek, dfeuer, gibiansky, rwbarton, thomie, mpickering, carter
      
      GHC Trac Issues: #10843, #10855
      
      Differential Revision: https://phabricator.haskell.org/D4260
      be84823b
  6. 26 Jan, 2018 1 commit
    • Matthías Páll Gissurarson's avatar
      Sort valid substitutions for typed holes by "relevance" · cbdea959
      Matthías Páll Gissurarson authored and Ben Gamari's avatar Ben Gamari committed
      This is an initial attempt at tackling the issue of how to order the
      suggestions provided by the valid substitutions checker, by sorting
      them by creating a graph of how they subsume each other. We'd like to
      order them in such a manner that the most "relevant" suggestions are
      displayed first, so that the suggestion that the user might be looking
      for is displayed before more far-fetched suggestions (and thus also
      displayed when they'd otherwise be cut-off by the
      `-fmax-valid-substitutions` limit). The previous ordering was based on
      the order in which the elements appear in the list of imports, which I
      believe is less correlated with relevance than this ordering.
      
      A drawback of this approach is that, since we now want to sort the
      elements, we can no longer "bail out early" when we've hit the
      `-fmax-valid-substitutions` limit.
      
      Reviewers: bgamari, dfeuer
      
      Reviewed By: dfeuer
      
      Subscribers: dfeuer, rwbarton, thomie, carter
      
      Differential Revision: https://phabricator.haskell.org/D4326
      cbdea959
  7. 21 Jan, 2018 2 commits
    • Takenobu Tani's avatar
      Implement underscores in numeric literals (NumericUnderscores extension) · 4a13c5b1
      Takenobu Tani authored and Ben Gamari's avatar Ben Gamari committed
      Implement the proposal of underscores in numeric literals.
      Underscores in numeric literals are simply ignored.
      
      The specification of the feature is available here:
      https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/000
      9-numeric-underscores.rst
      
      For a discussion of the various choices:
      https://github.com/ghc-proposals/ghc-proposals/pull/76
      
      Implementation detail:
      
      * Added dynamic flag
        * `NumericUnderscores` extension flag is added for this feature.
      
      * Alex "Regular expression macros" in Lexer.x
        * Add `@numspc` (numeric spacer) macro to represent multiple
          underscores.
        * Modify `@decimal`, `@decimal`, `@binary`, `@octal`, `@hexadecimal`,
          `@exponent`, and `@bin_exponent` macros to include `@numspc`.
      
      * Alex "Rules" in Lexer.x
        * To be simpler, we have only the definitions with underscores.
          And then we have a separate function (`tok_integral` and `tok_frac`)
          that validates the literals.
      
      * Validation functions in Lexer.x
        * `tok_integral` and `tok_frac` functions validate
          whether contain underscores or not.
          If `NumericUnderscores` extensions are not enabled,
          check that there are no underscores.
        * `tok_frac` function is created by merging `strtoken` and
          `init_strtoken`.
        * `init_strtoken` is deleted. Because it is no longer used.
      
      * Remove underscores from target literal string
        * `parseUnsignedInteger`, `readRational__`, and `readHexRational} use
          the customized `span'` function to remove underscores.
      
      * Added Testcase
        * testcase for NumericUnderscores enabled.
            NumericUnderscores0.hs and NumericUnderscores1.hs
        * testcase for NumericUnderscores disabled.
            NoNumericUnderscores0.hs and NoNumericUnderscores1.hs
        * testcase to invalid pattern for NumericUnderscores enabled.
            NumericUnderscoresFail0.hs and NumericUnderscoresFail1.hs
      
      Test Plan: `validate` including the above testcase
      
      Reviewers: goldfire, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: carter, rwbarton, thomie
      
      GHC Trac Issues: #14473
      
      Differential Revision: https://phabricator.haskell.org/D4235
      4a13c5b1
    • Alp Mestanogullari's avatar
      tentative improvement to callstack docs · 5edb18a9
      Alp Mestanogullari authored and Ben Gamari's avatar Ben Gamari committed
      This is an attempt at clarifying the docs for HasCallStack in both the
      user guide and libraries/base/GHC/Stack/Types.hs. The example used right
      now is built around an hypothetical 'error' function that doesn't itself
      print call stacks, and the fact that this doesn't hold makes it all
      confusing, see #14635.
      
      Reviewers: hvr, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: rwbarton, thomie, carter
      
      GHC Trac Issues: #14635
      
      Differential Revision: https://phabricator.haskell.org/D4317
      5edb18a9
  8. 03 Jan, 2018 2 commits
  9. 02 Jan, 2018 1 commit
  10. 21 Dec, 2017 1 commit
  11. 19 Dec, 2017 1 commit
  12. 18 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Fix scoping of pattern-synonym existentials · f1fe5b4a
      Simon Peyton Jones authored
      This patch fixes Trac #14998, where we eventually decided that
      the existential type variables of the signature of a pattern
      synonym should not scope over the pattern synonym.
      
      See Note [Pattern synonym existentials do not scope] in TcPatSyn.
      f1fe5b4a
  13. 11 Dec, 2017 1 commit
  14. 15 Nov, 2017 1 commit
  15. 06 Nov, 2017 1 commit
  16. 03 Nov, 2017 1 commit
  17. 02 Nov, 2017 2 commits
  18. 25 Oct, 2017 1 commit
    • Joachim Breitner's avatar
      Make language extensions their own category in the documentation · 61f1b46e
      Joachim Breitner authored
      I.e. instead of
      
          .. ghc-flag:: -XUnboxedTuples
              :shortdesc: Enable the use of unboxed tuple syntax.
              :type: dynamic
              :reverse: -XNoUnboxedTuples
              :category:
      
      one simply writes
      
          .. extension:: UnboxedTuples
              :shortdesc: Enable the use of unboxed tuple syntax.
      
      This allows language extensions to be referenced as
      
          If :extension:`UnboxedTuples` is enabled, then...
      
      This directive still creates the entries for the `-XUnboxedTuples` flag,
      so in particular,
      
          Set :ghc-flag:`-XUnboxedTuples` if you have to.
      
      still works, and lists of flags in general (e.g. for the manpage)
      include these.
      
      I also removed lots of links from the shortdesc of the extensions, when
      this link simply points to the section where the extension is defined.
      
      I removed the list of `-X` flags from the flag reference table, but added a
      table of extension under “10.1. Language options”
      
      Lots of text in the manual now refers to “extension `Foo`” rather than
      “flag `-XFoo`”.
      
      I consider `-XFoo` a historic artifact that stems from when language
      extensions were really just flags. These days, the use of `-XFoo` is
      (IMHO) deprecated: You should be using `LANGUAGE Foo`, or maybe the
      appropriate field in a `.cabal` file. See 9278994a which did this change
      to error messages already.
      
      Differential Revision: https://phabricator.haskell.org/D4112
      61f1b46e
  19. 20 Oct, 2017 1 commit
  20. 19 Oct, 2017 1 commit
  21. 17 Oct, 2017 1 commit
    • Joachim Breitner's avatar
      Improve user’s guide around deriving · 317aa966
      Joachim Breitner authored
      In particular:
       * add an intro to “10.6. Extensions to the “deriving” mechanism” giving
         an overview,
       * make the various sections on `-XDerivingFoo` subsections of
         “10.6.3. Deriving instances of extra classes (Data, etc.)”
       * Move the reference anchors for the various `DerivingFoo` extensions
         to a more appropriate spot.
       * Add subsection “10.6.6.1. Default deriving strategy” to the
         deriving section (#14357)
      317aa966
  22. 15 Oct, 2017 1 commit
  23. 13 Oct, 2017 1 commit
    • Ryan Scott's avatar
      Delete obsolete docs on GADT interacton with TypeApplications · 2be55b85
      Ryan Scott authored
      Even since ef26182e, this section of
      the users' guide is wrong, as there are no longer special rules for
      the order of type variables in GADT constructors' type signatures
      vis-à-vis visible type application. As a result, this section can
      simply be deleted, as there is no longer anything interesting to say
      about the topic.
      2be55b85
  24. 26 Sep, 2017 1 commit
  25. 25 Sep, 2017 1 commit
  26. 05 Sep, 2017 1 commit
    • Ryan Scott's avatar
      Implicitly bind kind variables in type family instance RHSes when it's sensible · 0829821a
      Ryan Scott authored
      Summary:
      Before, there was a discrepancy in how GHC renamed type synonyms as
      opposed to type family instances. That is, GHC would accept definitions like
      this one:
      
      ```lang=haskell
      type T = (Nothing :: Maybe a)
      ```
      
      However, it would not accept a very similar type family instance:
      
      ```lang=haskell
      type family   T :: Maybe a
      type instance T = (Nothing :: Maybe a)
      ```
      
      The primary goal of this patch is to bring the renaming of type family
      instances up to par with that of type synonyms, causing the latter definition
      to be accepted, and fixing #14131.
      
      In particular, we now allow kind variables on the right-hand sides of type
      (and data) family instances to be //implicitly// bound by LHS type (or kind)
      patterns (as opposed to type variables, which must always be explicitly
      bound by LHS type patterns only). As a consequence, this allows programs
      reported in #7938 and #9574 to typecheck, whereas before they would
      have been rejected.
      
      Implementation-wise, there isn't much trickery involved in making this happen.
      We simply need to bind additional kind variables from the RHS of a type family
      in the right place (in particular, see `RnSource.rnFamInstEqn`, which has
      undergone a minor facelift).
      
      While doing this has the upside of fixing #14131, it also made it easier to
      trigger #13985, so I decided to fix that while I was in town. This was
      accomplished by a careful blast of `reportFloatingKvs` in `tcFamTyPats`.
      
      Test Plan: ./validate
      
      Reviewers: simonpj, goldfire, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #13985, #14131
      
      Differential Revision: https://phabricator.haskell.org/D3872
      0829821a
  27. 02 Sep, 2017 1 commit
    • Ryan Scott's avatar
      Disallow bang/lazy patterns in the RHSes of implicitly bidirectional patsyns · 5dd6b13c
      Ryan Scott authored
      Summary:
      GHC was allowing implicitly bidirectional pattern synonyms with bang
      patterns and irrefutable patterns in the RHS, like so:
      
      ```lang=haskell
      pattern StrictJust a = Just !a
      ```
      
      This has multiple problems:
      
      1. `Just !a` isn't a valid expression, so it feels strange to allow it in an
         implicitly bidirectional pattern synonym.
      2. `StrictJust` doesn't provide the strictness properties one would expect
         from a strict constructor. (One could imagine a design where the
         `StrictJust` builder infers a bang pattern for its pattern variable, but
         accomplishing this inference in a way that accounts for all possible
         patterns on the RHS, including other pattern synonyms, is somewhat
         awkward, so we do not pursue this design.)
      
      We nip these issues in the bud by simply disallowing bang/irrefutable patterns
      on the RHS.
      
      Test Plan: make test TEST="T14112 unidir"
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #14112
      
      Differential Revision: https://phabricator.haskell.org/D3896
      5dd6b13c
  28. 01 Sep, 2017 1 commit
  29. 26 Aug, 2017 1 commit
  30. 19 Aug, 2017 1 commit
    • patrickdoc's avatar
      users_guide: Convert mkUserGuidePart generation to a Sphinx extension · cf8ab1ce
      patrickdoc authored and Ben Gamari's avatar Ben Gamari committed
      This removes all dependencies the users guide had on `mkUserGuidePart`.
      The generation of the flag reference table and the various pieces of the
      man page is now entirely contained within the Spinx extension
      `flags.py`. You can see the man page generation on the orphan page
      https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ghc.html
      
      The extension works by collecting all of the meta-data attached to the
      `ghc-flag` directives and then formatting and displaying it at
      `flag-print` directives. There is a single printing directive that can
      be customized with two options, what format to display (table, list, or
      block of flags) and an optional category to limit the output to
      (verbosity, warnings, codegen, etc.).
      
      New display formats can be added by creating a function
      `generate_flag_xxx` (where `xxx` is a description of the format) which
      takes a list of flags and a category and returns a new `xxx`. Then just
      add a reference in the dispatch table `handlers`. That display can now
      be run by passing `:type: xxx` to the `flag-print` directive.
      
      `flags.py` contains two maps of settings that can be adjusted. The first
      is a canonical list of flag categories, and the second sets default
      categories for files.
      
      The only functionality that Sphinx could not replace was the
      `what_glasgow_exts_does.gen.rst` file. `mkUserGuidePart` actually just
      reads the list of flags from `compiler/main/DynFlags.hs` which Sphinx
      cannot do. As the flag is deprecated, I added the list as a static file
      which can be updated manually.
      
      Additionally, this patch updates every single documented flag with the
      data from `mkUserGuidePart` to generate the reference table.
      
      Fixes #11654 and, incidentally, #12155.
      
      Reviewers: austin, bgamari
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #11654, #12155
      
      Differential Revision: https://phabricator.haskell.org/D3839
      cf8ab1ce
  31. 17 Aug, 2017 3 commits
  32. 15 Aug, 2017 1 commit
  33. 07 Aug, 2017 1 commit
  34. 27 Jul, 2017 1 commit
    • Richard Eisenberg's avatar
      Fix #12369 by being more flexible with data insts · 42392383
      Richard Eisenberg authored
      Previously, a data family's kind had to end in `Type`,
      and data instances had to list all the type patterns for the
      family. However, both of these restrictions were unnecessary:
      
      - A data family's kind can usefully end in a kind variable `k`.
        See examples on #12369.
      
      - A data instance need not list all patterns, much like how a
        GADT-style data declaration need not list all type parameters,
        when a kind signature is in place. This is useful, for example,
        here:
      
          data family Sing (a :: k)
          data instance Sing :: Bool -> Type where ...
      
      This patch also improved a few error messages, as some error
      plumbing had to be moved around.
      
      See new Note [Arity of data families] in FamInstEnv for more
      info.
      
      test case: indexed-types/should_compile/T12369
      42392383