purescript

This is an automated preview release. Get the latest stable release here.

New features:

• Add --exclude-file to more commands (#4530 by @JordanMartinez)

  This CLI arg was added to the compile command, but not to other commands
  where such a usage would be relevant (e.g. docs, repl, graph, and ide).

• Enable passing source input globs via --source-globs-file path/to/file (#4530 by @JordanMartinez)

  --source-globs-file support has been added to the following commands:
  compile, docs, graph, ide, and publish.

  Due to a shell character limitation on Windows where a large list of
  source globs cannot be passed (e.g. purs compile ... glob1000/src/**/*.purs),
  source globs can be stored in a file according to the format below
  and the file is passed in instead via purs compile ---source-globs-file path/to/file.

  # Lines starting with '#' are comments.
  # Blank lines are ignored.
  # Otherwise, every line is a glob.
  
  .spago/foo-1.2.3/src/**/*.purs
  .spago/bar-2.3.3/src/**/*.purs
  my-package/src/**/*.purs
  my-package/tests/**/*.purs
  

  --source-globs-file is an optional argument. Mixing it with the normal source globs is fine.
  Assuming .spago/source-globs contains src/**/*.purs, each command below will use
  the same input globs:

  purs compile src/**/*.purs
  purs compile --source-globs .spago/source-globs
  purs compile --source-globs .spago/source-globs src/**/*.purs 
  

  In the command...

  purs compile inputGlob1 inputGlob2 --source-globs-file fileWithMoreGlobs --exclude-files excludeGlob1
  

  the files passed to the compiler are: all the files found by
  inputGlob1, inputGlob2, and all the globs listed in fileWithMoreGlobs
  minus the files found by excludeGlob1.

This is an automated preview release. Get the latest stable release here.

Bugfixes:

• Fix a compilation memory regression for very large files (#4521 by @mjrussell)

  When compiling a a very large file (>12K lines)
  the CSE pass could balloon memory and result in increased
  compilation times.

  This fix uses a strict Map instead of a lazy Map to avoid
  building up unnecessary thunks during the optimization pass.

• Fix two space leaks while compiling many modules (#4517 by @MonoidMusician)

  The first would interleave compilation of too many modules at once, which
  would increase memory usage, especially for single threaded builds with
  +RTS -N1 -RTS. Now the number of concurrent modules is limited to
  the number of threads available to the
  GHC runtime system.

  The second would hold on to memory from modules that compiled with warnings
  until the end of the build when the warnings were printed and the memory freed.
  This is now fixed with additional NFData instances.

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

New features:

• Replace UnusableDeclaration with updated NoInstanceFound (#4513 by @JordanMartinez)

  Previously, the following type class would be invalid
  because there was no way for the compiler to infer
  which type class instance to select because
  the type variable in the class head a was
  not mentioned in bar's type signature:

  class Foo a where
    bar :: Int
  

  The recently-added visible type applications (VTAs)
  can now be used to guide the compiler in such cases:

  class Foo a where bar :: Int
  instance Foo String where bar = 0
  someInt = bar @String -- use the `String` instance
  

  Without VTAs, the compiler
  will still produce an InstanceNotFound error, but this error
  has been updated to note which type variables in the class head
  can only be disambiguated via visible type applications.
  Given the following code

  class Single tyVarDoesNotAppearInBody where 
    useSingle :: Int
  
  single :: Int
  single = useSingle
  

  The error reported for useSingle will be:

  No type class instance was found for
  
    Main.Single t0
  
  The instance head contains unknown type variables.
  
  
  Note: The following type class members found in the expression require visible type applications 
  to be unambiguous (e.g. tyClassMember @Int).
    Main.useSingle
      tyNotAppearInBody
  

  For a multiparameter typeclass with functional dependencies...

  class MultiFdBidi a b | a -> b, b -> a where
    useMultiFdBidi :: Int
  
  multiFdBidi :: Int
  multiFdBidi = useMultiFdBidi
  

  ...the "Note" part is updated to read

  Note: The following type class members found in the expression require visible type applications 
  to be unambiguous (e.g. tyClassMember @Int).
    Main.useMultiFdBidi
      One of the following sets of type variables:
        a
        b
  

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

New features:

• Move the closed record update optimization (#4489 by @rhendric)

  For consumers of CoreFn like alternate backends, the optimization of
  replacing a closed record update with an object literal has now been moved to
  the point of desugaring CoreFn into JS. The ObjectUpdate expression
  constructor now contains a Maybe field holding a list of record labels to
  be copied as-is, for backends that want to perform this optimization also.

• Allow instances that require Fail to be empty (#4490 by @rhendric)

  A class instance declaration that has Prim.TypeError.Fail as a constraint
  will never be used. In light of this, such instances are now allowed to have
  empty bodies even if the class has members.

  (Such instances are still allowed to declare all of their members, and it is
  still an error to specify some but not all members.)

Bugfixes:

• Stop emitting warnings for wildcards in Visible Type Applications (#4492 by @JordanMartinez)

  Previously, the below usage of a wildcard (i.e. _) would
  incorrectly cause the compiler to emit a warning.

  f :: forall @a. a -> a
  f = identity
  
  x :: { x :: Int }
  x = f @{ x :: _ } { x: 42 }
  

• Infer types using VTA inside a record (#4501 by @JordanMartinez)

  Previously, use would fail to compile
  because the v type variable would not be inferred
  to String. Now the below code compiles:

  reflect :: forall @t v . Reflectable t v => v
  reflect = reflectType (Proxy @t)
  
  use :: String
  use = show { asdf: reflect @"asdf" }
  

Internal:

• Use gh for release artifacts (#4493 by @rhendric, #4509 by @JordanMartinez)

• Stop triggering CI on non-code-related changes (e.g. Readme) (#4502 by @JordanMartinez)

New features:

• Move the closed record update optimization (#4489 by @rhendric)

  For consumers of CoreFn like alternate backends, the optimization of
  replacing a closed record update with an object literal has now been moved to
  the point of desugaring CoreFn into JS. The ObjectUpdate expression
  constructor now contains a Maybe field holding a list of record labels to
  be copied as-is, for backends that want to perform this optimization also.

• Allow instances that require Fail to be empty (#4490 by @rhendric)

  A class instance declaration that has Prim.TypeError.Fail as a constraint
  will never be used. In light of this, such instances are now allowed to have
  empty bodies even if the class has members.

  (Such instances are still allowed to declare all of their members, and it is
  still an error to specify some but not all members.)

Bugfixes:

• Stop emitting warnings for wildcards in Visible Type Applications (#4492 by @JordanMartinez)

  Previously, the below usage of a wildcard (i.e. _) would
  incorrectly cause the compiler to emit a warning.

  f :: forall @a. a -> a
  f = identity
  
  x :: { x :: Int }
  x = f @{ x :: _ } { x: 42 }
  

• Infer types using VTA inside a record (#4501 by @JordanMartinez)

  Previously, use would fail to compile
  because the v type variable would not be inferred
  to String. Now the below code compiles:

  reflect :: forall @t v . Reflectable t v => v
  reflect = reflectType (Proxy @t)
  
  use :: String
  use = show { asdf: reflect @"asdf" }
  

Internal:

• Use gh for release artifacts (#4493 by @rhendric)

• Stop triggering CI on non-code-related changes (e.g. Readme) (#4502 by @JordanMartinez)

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

New features:

• Implement visible type applications

  The compiler now supports visible type applications, allowing the user to instantiate one or more "visible" type variables to a specific type.

  A "visible" type variable is a type variable in a forall binder that appears prefixed with an @, like the following example:

  id :: forall @a. a -> a  -- or with kinds: `forall (@a :: Type). a -> a`
  id a = a
  

  We can then use type application syntax to instantiate this binding to a specific type:

  idInt :: Int -> Int
  idInt = id @Int
  
  example :: Int
  example = id @Int 0
  

  Type variables appearing in class or data are automatically visible, meaning that they do not require annotations:

  data Maybe a = Just a | Nothing
  
  nothingInt :: Maybe Int
  nothingInt = Nothing @Int
  
  class Identity a where
    identity :: a -> a
  
  instance Identity Int where
    identity a = a
  
  identityInt = identity @Int
  
  -- This throws a `NoInstanceFound` error.
  identityNumber = identity @Number
  

  Lastly, visible type variables can also be skipped with a wildcard (i.e. _)

  data Either a b = Left a | Right b
  
  example = Left @_ @Number 0
  

  Note that performing a type application with a type that has no visible type variables throws an error:

  module Main where
  
  id :: forall a. a -> a
  id a = a
  
  idInt = id @Int
  
  {-
  Error found:
  in module Main
  at Main.purs:6:9 - 6:16 (line 6, column 9 - line 6, column 16)
  
    An expression of polymorphic type
    with the invisible type variable a:
                    
      forall a. a -> a
                    
    cannot be applied to:
       
      Int
       
  
  while inferring the type of id
  in value declaration idInt
  
  See https://github.com/purescript/documentation/blob/master/errors/CannotApplyExpressionOfTypeOnType.md for more information,
  or to contribute content related to this error.
  -}
  

  Similarly, monomorphic types also cannot be used for type applications:

  module Main where
  
  idInt :: Int -> Int
  idInt a = a
  
  example = idInt @Int
  
  {-
  Error found:
  in module Main
  at Main.purs:6:11 - 6:21 (line 6, column 11 - line 6, column 21)
  
    An expression of monomorphic type:
              
      Int -> Int
              
    cannot be applied to:
       
      Int
       
  
  while inferring the type of idInt
  in value declaration example
  
  See https://github.com/purescript/documentation/blob/master/errors/CannotApplyExpressionOfTypeOnType.md for more information,
  or to contribute content related to this error.
  -}
  

• Exclude files from compiler input (#4480 by @i-am-the-slime)

  The compiler now supports excluding files from the globs given to it as input.
  This means there's now a new option for purs compile, namely
  --exclude-files (or the short version -x):

  > purs compile --help
  Usage: purs compile [FILE] [-x|--exclude-files ARG] [-o|--output ARG] ...
  
    Compile PureScript source files
  
  Available options:
    -h,--help                Show this help text
    FILE                     The input .purs file(s).
    -x,--exclude-files ARG   Glob of .purs files to exclude from the supplied
                            files.
    ...
  

  This allows you to keep related files closer together (that is, colocate them).

  Consider a setup like the following:

  src/
      Main.purs
      View/
          LoginPage.purs
          LoginPageTest.purs
          LoginPageStories.purs
  

  In order to exclude the files in the example above you can now invoke purs
  like this and it will only compile LoginPage.purs:

  purs compile "src/**/*.purs" --exclude-files "src/**/*Stories.purs" -x "src/**/*Test.purs"
  

  With spago, the equivalent command is:

  spago build --purs-args '-x "src/**/*Test.purs" -x "src/**/*Stories.purs"'
  

This is an automated preview release. Get the latest stable release here.

This is an automated preview release. Get the latest stable release here.

New features:

• Add release artifacts for Linux and macOS running on the ARM64 architecture. (#4455 by @f-f)

Bugfixes:

• Fix prerelease version number on macOS (#4461 by @rhendric)

• Consider fixity declarations during linting (#4462 by @ozkutuk)

• Defer monomorphization for data constructors (#4376 by @purefunctor)

  In 0.15.4 and earlier, the compiler monomorphizes type
  constructors early, yielding the following type:

  > :t Nothing
  forall (a1 :: Type). Maybe a1
  
  > :t { a : Nothing }
  forall (a1 :: Type).
    { a :: Maybe a1
    }
  

  With this change, the monomorphization introduced in
  #835 is
  deferred to only when it's needed, such as when constructors are
  used as values inside of records.

  > :t Nothing
  forall a. Maybe a
  
  > :t { a : Nothing }
  forall (a1 :: Type).
    { a :: Maybe a1
    }
  

  Also as a consequence, record updates should not throw
  ConstrainedTypeUnified in cases such as:

  v1 :: { a :: Maybe Unit }
  v1 = { a : Just Unit }
  
  v2 :: { a :: Maybe Unit }
  v2 = let v3 = v1 { a = mempty } in v3
  

• Update installer to version 0.3.5 to support ARM builds (#4468 and #4469 by @rhendric)

• Fix exhaustiveness checking to account for case guards (#4467 by @purefunctor)

Internal:

• Refactor module imports to make identifiers' origins obvious (#4451 by @JordanMartinez)

• Require comments not to cause Haddock warnings (#4456 by @rhendric)