title: What other ways can state be handled in a pure functional language besides with Monads?
body: <p>So I started to wrap my head around Monads (used in Haskell). I'm curious what other ways IO or state can be handled in a pure functional language (both in theory or reality). For example, there is a logical language called "mercury" that uses "effect-typing". In a program such as haskell, how would effect-typing work? How does other systems work? </p>