Difference between revisions of "PreludeTour"
From HaskellWiki
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| − | = A Tour of the Haskell Prelude = | + | == A Tour of the Haskell Prelude == |
| + | |||
| + | |||
| + | ;'''abs''': | ||
| + | {| border="0" cellpadding="4" | ||
| + | |- | ||
| + | | ''type:'' || <hask>abs :: Num a => a -> a</hask> | ||
| + | |- | ||
| + | | ''description:'' || returns the absolute value of a number. | ||
| + | |- | ||
| + | | ''definition:'' | ||
| + | | <haskell> | ||
| + | abs x | ||
| + | | x >= 0 = x | ||
| + | | otherwise = -x | ||
| + | </haskell> | ||
| + | |- | ||
| + | | ''usage:'' | ||
| + | | <pre> | ||
| + | Prelude> abs (-3) | ||
| + | 3 | ||
| + | </pre> | ||
| + | |} | ||
| + | |||
| + | ;'''all''': | ||
| + | {| border="0" cellpadding="4" | ||
| + | |- | ||
| + | | ''type:'' || <hask>all :: (a -> Bool) -> [a] -> Bool</hask> | ||
| + | |- | ||
| + | | ''description:'' || pplied to a predicate and a list, returns True if all elements of the list satisfy the predicate, and False otherwise. Similar to the function any. | ||
| + | |- | ||
| + | | ''definition:'' | ||
| + | | <haskell> | ||
| + | all p xs = and (map p xs) | ||
| + | </haskell> | ||
| + | |- | ||
| + | | ''usage:'' | ||
| + | | <pre> | ||
| + | Prelude> all (<11) [1..10] | ||
| + | True | ||
| + | Prelude> all isDigit "123abc" | ||
| + | False | ||
| + | </pre> | ||
| + | |} | ||
Revision as of 13:21, 26 October 2009
A Tour of the Haskell Prelude
- abs
| type: | abs :: Num a => a -> a
|
| description: | returns the absolute value of a number. |
| definition: | abs x
| x >= 0 = x
| otherwise = -x
|
| usage: | Prelude> abs (-3) 3 |
- all
| type: | all :: (a -> Bool) -> [a] -> Bool
|
| description: | pplied to a predicate and a list, returns True if all elements of the list satisfy the predicate, and False otherwise. Similar to the function any. |
| definition: | all p xs = and (map p xs)
|
| usage: | Prelude> all (<11) [1..10] True Prelude> all isDigit "123abc" False |