[Haskell] ST vs State

Federico Squartini federico.squartini at googlemail.com
Wed May 30 05:59:55 EDT 2007

But they are very similar! At least superficially.

They are both based on the notion of state transformer. Moreover in
the original paper about the ST monad:

The authors say:

"In this paper we describe a way to express stateful algorithms in
non-strict, purely functional languages".  And almost everywhere in
the paper looks as if they are talking about a normal State monad.

I suppose there is something "under the hood" which makes them
different, but I cannot figure out what.


> Very very different.
> -- Don

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