let floating
let floating
(programming)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 canautomatically transform this to
t = sqrt 4f x = x + t
Making t into a global constant which need only be evaluatedat most once, rather than every time f is called. The generalidea is to float each subexpression as far out (toward thetop level) as possible to maximise sharing.