<programming> A program transformation
used in functional programming
to implement full laziness
E.g. the function
f x = x + sqrt 4
can be expressed as
f x = let t = sqrt 4 in x + t
but note that t does not depend on the argument x so we can automatically transform this to
t = sqrt 4 f x = x + t
Making t into a global constant which need only be evaluated at most once, rather than every time f is called.
The general idea is to float each subexpression as far out (toward the top level) as possible to maximise sharing.