[Haskell-cafe] Re: What is a rigid type variable?

[Ben Franksen]

Ryan Ingram wrote:
> To answer the question in the subject:
> 
>>From "Simple unification-based type inference for GADTs",
> Peyton-Jones, et al.  ICFP 2006.
> http://research.microsoft.com/users/simonpj/papers/gadt/
> 
> "Instead of "user-specified type", we use the briefer term rigid
> type to describe a type that is completely specified, in some
> direct fashion, by a programmer-supplied type annotation."
> 
> So a rigid type is any type specified by a programmer type signature.
> All other types are "wobbly".

Wow. Such a short and clear explanation. I have been wondering for some time
what exactly this 'rigid' means... Please somebody who understands stuff
like that better than me put it on some wiki page. It's obviously a FAQ.

BTW, do we have a FAQ page? I think we should have one.

Cheers
Ben
(a little behind on cafe, catching up...)