Synonym Type Constructors

Ashley Yakeley
Mon, 19 Feb 2001 03:53:11 -0800

I don't know if this is a bug in Hugs 98, or whether it's a 
misunderstanding of mine.

The Haskell 98 Report Sec. 4.2.2 claims that 'type' introduces a new type 
constructor. Yet it doesn't seem possible to declare the type constructor 
an instance of a class:

class MyClass c where
	foo :: a -> c a

type T m = IO m

instance MyClass T where
	foo = return

Hugs gives:
(line 6): Not enough arguments for type synonym "T"

So is T a real type constructor or not?

Ashley Yakeley, Seattle WA