[Haskell-cafe] On to applicative

Vo Minh Thu noteed at gmail.com
Tue Aug 31 13:17:02 EDT 2010

2010/8/31 michael rice <nowgate at yahoo.com>
> "Learn You a Haskell ..."  says that (->) is a type just like Either. Where can I find its type definition?

You can't define it *in* Haskell as user code. It is a built-in infix
type constructor (Either or Maybe are type constructors too, not just
types). In fact, if you want to implement a simple, typed functional
language, you'll find it is the only built-in type constructor you
have to implement (as the implementor of the language).

  Show a => a
is a type too, but you won't find a definition for 'a' or for '=>'.
All those things are defined by the language.


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