Re: [Haskell-cafe] Simple but interesting (for me) problem

2009/10/21 michael rice

There's a thread on the plt-scheme list about creating a function of NO arguments named NEXT that just returns the number of times it's been called, a piece of cake in Scheme, but how would one do this in Haskell? Would the best approach be to use a State monad?

If you really want no argument, not just syntactically in the do notation, you need ST or IO. Furthermore, you need ST or IO to allocate a mutable variable that is accessible only to the next function. Cheers, Thu