Difference between revisions of "PreludeTour"

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(Tour was cut short for some reason)
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== 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