[Haskell-beginners] Re: some terminology

Heinrich Apfelmus apfelmus at quantentunnel.de
Thu Aug 13 05:14:17 EDT 2009

Michael P Mossey wrote:
> I was looking at some code, saw a variable x, and said to myself, "Ah
> that variable is a monad." Then I realized "Monad" is the name of a type
> class. So maybe x should be called "an instance of a Monad." I think the
> word "instance" in this case is OO-like; but in Haskell "instance"
> refers to a type that is an instance of a type class. Or maybe it can
> refer to both? And Monad is a type class, not a type. Maybe I need the
> phrase "monadic type" to refer to an instance of a type class. So maybe
> x is just "a variable of a monadic type"?

One common nomenclature is to say that  x  is a "monadic action" or just
 "action" for short. That's the terminology used in the

  Simon Peyton Jones.  Tackling the awkward squad.




More information about the Beginners mailing list