View Source: LazyEvaluation - Waikato Linux Users Group

Edit PageHistory Diff Info LikePages

LazyEvaluation is an approach that a ProgrammingLanguage can take to evaluating expressions. With LazyEvaluation a function is passed whole expressions as arguments, and does not evaluate them until it needs their values.

You could call [C]'s __&&__ and __||__ operators lazy operators: they do not always evaluate their second arguments. But this is a built-in feature of [C] and there's no way to specify user defined operators that work that way. In [Haskell] f.ex, which is the most widely used lazy functional programming language, you can.

I/O is problematic in lazy languages. Lazy languages don't assume a linear flow of time: you have to model that explicitly in your programs! Programmers need to provide some way to keep I/O operations in the correct sequence; in [Haskell] this is done using a data structure called the "monad".

3 pages link to LazyEvaluation:

Last edited on Sunday, March 7, 2004 9:34:34 am by AristotlePagaltzis

Edit PageHistory Diff Info LikePages