[Haskell-cafe] Purely logical programming language

[Matthias Görgens]

There are a number of ways to marry purely functional programming
languages with IO.  To name just two possibilities: Clean uses linear
types, threading exactly one "World" through functions, Haskell uses
Monads.

The model in Prolog, however, looks more like the model used in most
strict functional languages.  It uses impure predicates to affect the
outside world.  Do you know of any attempt to do for logic programming
what Monads did for functional programming?