资料来源 : Free On-Line Dictionary of Computing

filter promotion
     
        In a generate and test algorithm, combining part of the filter
        with the generator in order to reduce the number of potential
        solutions generated.  A trivial example:
     
        	filter (< 100) [1..1000]  ==>  [1..99]
     
        where [1..n] generates the list of integers from 1 to n.  Here
        the filter has been combined completely with the generator.
        This is an example of {fusion}.