let floating

<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.

Last updated: 1997-07-09

Nearby terms:

less than ♦ LessTif ♦ let floating ♦ letterbomb ♦ level 1 cache ♦ level 2 cache

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