Lazy -transformers +base
This module presents an identical interface to Control.Monad.ST, except that the monad delays evaluation of state operations until a value depending on them is required.
Mutable references in the lazy ST monad.
The call '(lazy e)' means the same as e, but lazy has a magical strictness property: it is lazy in its first argument, even though its semantics is strict.
Convert a lazy ST computation into a strict one.
Convert a strict ST computation into a lazy one. The strict state thread passed to strictToLazyST is not performed until the result of the lazy state thread it returns is demanded.