|Version 2 (modified by simonpj@…, 8 years ago) (diff)|
Infix Type Constructors
GHC allows type constructors to be infix operators (conops, beginning with :, but not including : itself).
Changes to the syntax may depend on whether CompositionAsDot is adopted, but roughly speaking we add
qtycon -> qconid | ( qconsym ) qtyconop -> qconsym | ` qconid `
And type gets an extra production:
type -> btype qtyconop type
(modulo FixityResolution). Also, there are obvious changes to the grammar for type, data, and newtype declarations.
- Infix type constructors, classes, and type variables in the GHC User's Guide.
- Add infix type constructors
- This is a straightforward generalisation, doesn't break any existing code, and improves the consistency of the syntax.
- Note that classes can be infix too; this is useful.
- Need to have a way to set the fixity of a type constructor T differently than the data constructor T (or not?).
- Need to allow infix notation in contexts
f :: (a :>: b) => bla blah
- Watch out for code like this (http://hackage.haskell.org/trac/ghc/ticket/1727)
infixr 5 `Foo` infixr 6 `Bar` data a `Foo` b = a `FOO` a `Bar` b data a `Bar` b = a `BAR` b