Difference between revisions of "PreludeTour"

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(Tour was cut short for some reason)
m (Reverted edits by Tomjaguarpaw (talk) to last revision by Bjpop)
 
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== A Tour of the Haskell Prelude ==
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;<span id="abs">'''abs'''</span>:
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{| border="0" cellpadding="4"
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|-
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| ''type:'' || <hask>abs :: Num a => a -> a</hask>
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|-
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| ''description:'' || returns the absolute value of a number.
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|-
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| ''definition:''
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| <haskell>
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abs x
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| x >= 0 = x
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| otherwise = -x
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</haskell>
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|-
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| ''usage:''
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| <pre>
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Prelude> abs (-3)
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3
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</pre>
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|}
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;<span id="all">'''all'''</span>:
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{| border="0" cellpadding="4"
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|-
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| ''type:'' || <hask>all :: (a -> Bool) -> [a] -> Bool</hask>
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|-
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| ''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]].
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|-
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| ''definition:''
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| <haskell>
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all p xs = and (map p xs)
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</haskell>
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|-
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| ''usage:''
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| <pre>
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Prelude> all (<11) [1..10]
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True
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Prelude> all isDigit "123abc"
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False
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</pre>
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|}

Latest revision as of 15:19, 6 February 2021

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: 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:
all p xs = and (map p xs)
usage:
Prelude> all (<11) [1..10]
True
Prelude> all isDigit "123abc"
False