purescript

Breaking Changes

• The body of a guarded expression must now be indented past the guard. For example, this is valid:

positive n | n > 0 = true
positive _ = false

but this is not:

positive n | n > 0 
  = true
positive _ = false

New Features

• Type wildcards are now supported (#287, @paf31)

Enhancements

• Allow unquoted keywords as key names in record literals (#606, @michaelficarra)
• Import instances when referencing qualified values (#667, @garyb)
• Multiple guard clauses are now supported (#294, @paf31)
• Type check let declarations immediately in psci (#615, @garyb)

• Prevent psci and psc-make from rebuilding everything on every build #692

For more information on PureScript, see the purescript.org website.

Breaking Changes

• The Alternative type class hierarchy was refactored. See here.
• --runtime-type-checks has been removed. The recommended approach is to use purescript-foreign. (@garyb)
• The Unit type is now used in the Prelude and core libraries to represent values containing no data. (@garyb)
• The Prelude is no longer distributed as a separate file, but is embedded in the compiler executables. (@paf31)
• docgen is now called psc-docs.

New Features

• Newtypes are now supported using the newtype keyword. The runtime representation of a newtype is identical to that of the contained type. (@garyb)
• Multiline string literals are now supported via triple-quote syntax, making FFI declarations much neater. (@phadej)
• Kind signatures on types and type constructor arguments are now supported. (@paf31)

Enhancements

• The runFnN and mkFnN families of functions are now inlined by the optimizer, making interop with JavaScript functions of multiple arguments much simpler. (@paf31)
• Tail call optimization has been improved for functions using case expressions. (@paf31)
• Saturated calls to data constructors are now optimized. (@garyb)
• A new Renamer module now renames identifiers which shadow other names in scope, which greatly simplies code generation. (@garyb)
• psci now provides the following new options:
  • :b to browse a module (@ardumont)
  • :s to show current imports or modules (@ardumont)
  • :k to find the kind of a type constructor (@5outh)
• The approach to checking whether a name is initialized in the generated JavaScript was simplified (@paf31)
• The dependency on the PureScript_paths module has been removed, which makes distribution via binaries simpler. (@paf31)
• Nested if blocks now get optimized. (@garyb)
• Generated code for type class dictionaries was simplified. (@garyb, @dylex)
• The code generator now inserts the version of psc into the file as a comment. (@co-dh)
• () is now valid syntax, referring to the empty row. (@paf31)
• The type checker will now display multiple errors for type errors in the same binding group. (@paf31)
• Imports can now specify hidden names using import ... hiding ( ... ) (@andreypopp)

Bug Fixes

• Binding group errors in type class members are now caught at compile time. (@dylex)
• Some errors related to type checking rows with duplicate labels were fixed. (@paf31)
• Some issues with the calculation of binding groups were fixed. (@paf31)
• Error messages for invalid case declarations are now generated. (@natefaubion)
• Some issues related to module exports were fixed. (@garyb)
• psci now checks imports for validity. (@Bogdanp)

Libraries

• The Alternative type class hierarchy was refactored (@joneshf, @garyb)
• The exceptions library no longer supports throwing exceptions of any type.
• The following libraries have been moved to the core PureScript organisation: (@garyb)
  • purescript-transformers
  • purescript-free
  • purescript-const
  • purescript-identity
  • purescript-lazy
  • purescript-distributive
  • purescript-bifunctors
  • purescript-contravariant
  • purescript-profunctors
  • purescript-maps

Documentation

• The PureScript book is now available.
• The PureScript wiki is now the main resource for compiler and library documentation.

This incremental release is provided to provide bug fixes and features required to compile the latest core libraries.

Breaking Changes

• Support for blocks has been removed. (paf31)

• Type class instances must now be named (paf31)

  instance showNumber :: Show Number where
    ...
  

• Prelude modules now follow a naming scheme similar to haskell (e.g. Data.Maybe, Control.Monad) (garyb)

• Many modules that were previously part of the Prelude have been split into individual libraries, now distributed via Bower (garyb)

• Multiple modules with the same name are now disallowed rather than merged (garyb)

• The Prelude module is now imported automatically. Conflicts can be avoided by using qualified imports or an explicit import list. (garyb, paf31)

• Overlapping instances are no longer allowed. The Prelude and core libraries have been updated accordingly. (paf31)

• Functor, Applicative, Monad are now part of a class heirarchy that include Apply and Bind. return is now an alias for pure. (joneshf, paf31, garyb)

• Semigroupoid is now a superclass of Category (garyb)

• (:) is now part of Prelude (garyb)

• (!!) has been renamed to Prelude.Unsafe.unsafeIndex and a safe version has been added to Data.Array (garyb)

New Features

• Multi parameter typeclasses (paf31)
• Superclasses (puffnfresh, paf31)
• FlexibleInstances and FlexibleContexts (paf31)
• Let bindings are now supported. The let keyword can introduce several local (possibly mutually recursive) bindings, along with optional type signatures. (paf31)
• where clauses are now supported in value declarations, with the same rules as let bindings (garyb)
• Empty data declarations and empty type classes are now supported (paf31)
• A new command line option --codegen controls which modules will have Javascript and externs generated (paf31)
• psc-make now generates CommonJS-compatible modules, which can be used with require() in node. psc still generates modules for use in the browser. (paf31, garyb)

Enhancements

• Pretty printing for row types was improved (garyb)
• Module names can now contain . (garyb)
• New optimizer rules have been added for code in the ST monad, to reproduce the functionality of the blocks feature, which has been removed (paf31)
• Pattern binders are now usable in lambda expression arguments (paf31)
• PSCI now has a :t command for checking the type of a value (paf31)
• Array pretty printing via show has been improved (joneshf)
• PSCI completions are sorted (joneshf)
• PSCI now has help commands (joneshf)
• PSCI history is in XDG config (joneshf)
• PSCI allows loading of modules from ~ paths (joneshf)
• PSCI can accept a list of modules to load on start from the command line (paf31)
• PSCI can now be configured using a .psci file in the current directory. If such a file exists, it should contain a list of commands to run on startup. (paf31)
• Type class instances are now named, to enable easier interop with Javascript (paf31)
• Class names no longer need to be qualified in instance declarations (garyb)
• Module exports can now be specified explicitly (garyb)
• Let bindings can now define functions with binders (paf31)
• Case statements and functions which do not pattern match on their arguments now generate smaller code (paf31)
• Imported type class instances are now exported (paf31)
• Some error messages were improved (paf31)
• Qualfied module imports are now supported as import qualified M as X (garyb)
• The escape check was removed, since it was too restrictive (paf31)
• The binary operator reordering step was greatly simplified (paf31)
• The Object type constructor can now be referenced explicitly as Prim.Object (with kind # * -> *) (paf31)
• Optimizations are now enabled by default and can be disabled with the --no-tco and --no-magic-do flags (garyb)
• Unary minus and signed numeric literals are now supported again (paf31, garyb)
• Type errors have been simplified, the full trace can be enabled with --verbose-errors or -v (paf31)
• Error messages now display source positions (paf31, garyb)
• The type classes implementation and code generation was greatly simplified (paf31)
• Object properties and row labels can now be accessed with arbitrary string names by using string literals (paf31)
• (++) is now an alias for the Semigroup operator (<>) (paf31)
• Error messages for classes with undefined or missing members have been improved (garyb)
• The SYB dependency was removed, and traversals rewritten by hand, for a large performance increase (paf31)

Bug Fixes

• The subsumes relation has been fixed for object types (paf31)
• sort no longer mutates arrays (joneshf)
• PSCI now evaluates expressions (joneshf)
• Overlapping variables in typeclass instances are rejected (paf31)
• A bug in the optimizer related to inlining was fixed (paf31)
• A type checker bug related to array literals was fixed (paf31)
• Externs files (--externs) are now working again (paf31)
• Precedence of backticked infix functions have been corrected (paf31)
• A bug which allowed some incorrect type class instances to pass the type checker was fixed (paf31)
• Type synonyms are no longer restricted to kind * (paf31)
• Negative number literals have been restored (garyb)
• If a type defined in a module appears in an exported declaration it must also be exported from the module (garyb)
• Error messages for unresolvable types or values include the declaration name again (garyb)
• Characters in string literals are now properly escaped (garyb)
• A module containing a single orphan type declaration and no other declarations now fails to compile (garyb)
• An error involving ordering of type class instances was fixed (garyb, paf31)
• Externs files no longer include fixity declarations for members that were removed as dead code (garyb)
• A bug which prevented sequence $ [Just 1] from typechecking was fixed (paf31)

Libraries

• Purescript libraries are now distributed via Bower. There are currently around 40 libraries available.

Plugins

• The grunt-purescript plugin has been updated to provide support for new command line options.
• There is a new gulp-purescript plugin available for compiling with Gulp.

Documentation

• There is a new hierarchy executable which will generate .dot diagrams based on the type class hierarchy of a module. The Prelude docs have been updated to include such a type class diagram. (joneshf)