PreludeTour: Difference between revisions

From HaskellWiki
No edit summary
(Tour was cut short for some reason)
Line 1: Line 1:
== A Tour of the Haskell Prelude ==


;<span id="abs">'''abs'''</span>:
{| 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>
|}
;<span id="all">'''all'''</span>:
{| border="0" cellpadding="4"
|-
| ''type:'' || <hask>all :: (a -> Bool) -> [a] -> Bool</hask>
|-
| ''description:'' || Applied 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 14:58, 6 February 2021