catflap.org Online Dictionary Query

  let floating
       
           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.
       
          (1997-07-09)