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| Newer page: | version 3 | Last edited on Sunday, October 26, 2003 7:41:03 am | by AristotlePagaltzis | Revert |
| Older page: | version 2 | Last edited on Sunday, February 16, 2003 5:31:15 pm | by GlynWebster | Revert |
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''Lazy evaluation'' is an approach that a ProgrammingLanguage can take to evaluating expressions. With ''lazy evaluation'' a function is passed whole expressions as arguments, and does not evaluate them until it needs their values. (I won't go into __why__ you'd want that, but there are good reasons.)
-[Haskell] is the most widely used lazy FunctionalLanguage
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+[Haskell] is the most widely used lazy FunctionalProgramming language
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You could call [C]'s __&&__ and __||__ operators lazy operators. They do not always evaluate their second arguments. This is is built-in feature of C though, you cannot define your own operators that work that way. In Haskell you can.
I/O is problematic in lazy languages. Programmers needs to provide some way to keep I/O operations in the correct sequence. Lazy languages don't assume a linear flow of time: you have to model that explicitly in your programs! Haskell uses a data structure called the [Monad] to control sequential operations.
