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# Infix Type Constructors

## Brief Explanation

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.

## References

- Infix type constructors, classes, and type variables in the GHC User's Guide.

## Tickets

- #78
- Add infix type constructors

## Pros

- This is a straightforward generalisation, doesn't break any existing code, and improves the consistency of the syntax.

## Cons

## Observations

- 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