...  ...  @@ 23,6 +23,39 @@ And `type` gets an extra production: 





(modulo [FixityResolution](fixityresolution)). Also, there are obvious changes to the grammar for `type`, `data`, and `newtype` declarations.









Secondly, I propose to allow varsyms to be used as type *constructors*. For example, currently "+" is a varsym, so at the type level it'd behave like a type *variable*






```wiki



data T (+) = MkT (Int + Int)



```









It's not impossible that this might be useful, although the binding site looks clumsy. But it misses a much more useful opportunity. What we *want* is to say






```wiki



data a + b = Left a  Right b



```









That is, we want to define the type *constructor*`(+)`. Currently we have to use the clumsy `:+` notation:






```wiki



data a :+ b = Left a  Right b



```









Yuk. **So I propose that varsyms can be used as type constructors, and not as type variables.**









You may say that is inconsistent, because at the value level you have to start data constructors with a ":". But the type level is already funny. The whole typefamily idea (beginning with type synonyms) defines things that begin with a capital letter, but which (unlike data constructors) are not head normal forms. By the time we have full typesynonym families, they really are \*functions\* as much as any valuelevel function is.









Some people use Haskell as a laboratory in which to write their cunning type ideas. In mathematics, operators are invariably toplevel type constructors (think of the type a+b). Mirroring this in Haskell would make the transcription more elegantly direct.









I can't think of any downsides, except the slight loss of consistency ("the hobgoblin of tiny minds").






## References






 [ Infix type constructors, classes, and type variables](http://www.haskell.org/ghc/docs/latest/html/users_guide/typeextensions.html#infixtycons) in the GHC User's Guide.

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