1. 26 Sep, 2020 1 commit
    • Arnaud Spiwack's avatar
      Pattern guards BindStmt always use multiplicity Many · 2707c4ea
      Arnaud Spiwack authored
      Fixes #18439 .
      
      The rhs of the pattern guard was consumed with multiplicity one, while
      the pattern assumed it was Many. We use Many everywhere instead.
      
      This is behaviour consistent with that of `case` expression. See #18738.
      2707c4ea
  2. 17 Jun, 2020 1 commit
    • Krzysztof Gogolewski's avatar
      Linear types (#15981) · 40fa237e
      Krzysztof Gogolewski authored
      This is the first step towards implementation of the linear types proposal
      (https://github.com/ghc-proposals/ghc-proposals/pull/111).
      
      It features
      
      * A language extension -XLinearTypes
      * Syntax for linear functions in the surface language
      * Linearity checking in Core Lint, enabled with -dlinear-core-lint
      * Core-to-core passes are mostly compatible with linearity
      * Fields in a data type can be linear or unrestricted; linear fields
        have multiplicity-polymorphic constructors.
        If -XLinearTypes is disabled, the GADT syntax defaults to linear fields
      
      The following items are not yet supported:
      
      * a # m -> b syntax (only prefix FUN is supported for now)
      * Full multiplicity inference (multiplicities are really only checked)
      * Decent linearity error messages
      * Linear let, where, and case expressions in the surface language
        (each of these currently introduce the unrestricted variant)
      * Multiplicity-parametric fields
      * Syntax for annotating lambda-bound or let-bound with a multiplicity
      * Syntax for non-linear/multiple-field-multiplicity records
      * Linear projections for records with a single linear field
      * Linear pattern synonyms
      * Multiplicity coercions (test LinearPolyType)
      
      A high-level description can be found at
      https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation
      Following the link above you will find a description of the changes made to Core.
      This commit has been authored by
      
      * Richard Eisenberg
      * Krzysztof Gogolewski
      * Matthew Pickering
      * Arnaud Spiwack
      
      With contributions from:
      
      * Mark Barbone
      * Alexander Vershilov
      
      Updates haddock submodule.
      40fa237e