Difference between revisions of "Functii din Prelude, A-F"

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[[Category:Ro]]
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[[Image:Haskelllogo-small-flag-RO-8.jpg|center|Haskell - Un limbaj functional pur]]
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  +
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Lista de functii des folosite, cu nume de la A la F.
  +
Pentru a vedea un exemplu de folosire (si tipul fiecarei functii) cautati numele ei mai jos pe pagina, cu Find-ul browser-ului.
  +
  +
abs - valoarea absoluta
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  +
all - predicatul e adevarat pe toata lista de argumente ?
  +
  +
and - conjunctie generalizata pe o lista de valori de tip Bool
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  +
any - exista o valoare pe lista care satisface predicatul (in engleza aceste intrebari se pun cu any)
  +
  +
atan - arctangenta
  +
  +
break - rupe o lista inaintea locului/elementului care satisface un predicat
  +
  +
ceiling - rotunjirea superioara la un intreg
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  +
chr - caracterul cu acel cod ascii, conversie numar - caracter
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  +
concat - concatenarea unui grup de liste , dat ca lista :) de liste
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  +
cos - cosinusul
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  +
digitToInt - transforma caracterul (daca e cifra) cifra in valoarea lui
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  +
div - impartirea intreaga
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  +
drop - arunca primele dintr-o lista
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  +
dropWhile - arunca primele care indeplinesc conditia
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-- folositor la a ajunge la primele elemente semnificative daca pui conditia invers
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  +
elem - apartine listei
  +
  +
error - genereaza eroare si poate avea orice tip, folositi-o deci oriunde
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exp - e(x)
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flip - schimba ordinea argumentelor unei functii cu doua arg
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filter - alege ce satisface predicatul, din lista data
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----
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<haskell>
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:t abs
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abs :: Num a => a -> a
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Prelude> abs -9
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ERROR - Illegal Haskell 98 class constraint in inferred type
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*** Expression : abs - 9
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*** Type : (Num a, Num (a -> a)) => a -> a
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Prelude> abs (-9)
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9
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Prelude> abs (-9.3)
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9.3
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Prelude>
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----
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Prelude> :t all
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all :: (a -> Bool) -> [a] -> Bool
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Prelude> all isDigit "12234678"
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True
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Prelude> all isDigit "danu"
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False
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Prelude>
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----
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lse
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Prelude> :t and
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and :: [Bool] -> Bool
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Prelude> and [True,True ,True]
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True
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Prelude> and [True,True ,True,False]
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False
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Prelude>
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----
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Prelude> :t atan
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atan :: Floating a => a -> a
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Prelude>
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Prelude> 4 * atan 1
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3.14159
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----
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relude> :t break
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break :: (a -> Bool) -> [a] -> ([a],[a])
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Prelude> break isDigit "R2D2"
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("R","2D2")
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Prelude> break isDigit "3PO"
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("","3PO")
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Prelude>
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Prelude> break isSpace "La Multi Ani 2008!"
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("La"," Multi Ani 2008!")
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Prelude>
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Prelude> break (==0) [5,24,23,2,1,0,-1]
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([5,24,23,2,1],[0,-1])
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Prelude>
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----
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Prelude> :t ceiling
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ceiling :: (RealFrac a, Integral b) => a -> b
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Prelude> ceiling 2.2
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3
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Prelude> ceiling 1.242
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2
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Prelude> ceiling 1.42
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2
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Prelude>
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----
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Prelude> :t chr
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chr :: Int -> Char
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Prelude> chr 66
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'B'
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Prelude> chr 65
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'A'
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Prelude> chr 32
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' '
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Prelude>
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----
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Prelude> :t concat
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concat :: [[a]] -> [a]
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Prelude> concat ["La", "Multi", "Ani","!"]
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"LaMultiAni!"
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Prelude>
  +
----
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Prelude> :t cos
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cos :: Floating a => a -> a
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Prelude> cos 0
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1.0
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Prelude>
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----
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relude> digitToInt "0"
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ERROR - Type error in application
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*** Expression : digitToInt "0"
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*** Term : "0"
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*** Type : String
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*** Does not match : Char
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Prelude> digitToInt '0'
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0
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Prelude> digitToInt '1'
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1
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Prelude> digitToInt '2'
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2
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Prelude> digitToInt '3'
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3
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Prelude> digitToInt '4'
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4
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Prelude> digitToInt 'u'
  +
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Program error: Char.digitToInt: not a digit
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  +
Prelude>
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----
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Prelude> :t div
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div :: Integral a => a -> a -> a
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Prelude> 10 `div` 3
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3
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Prelude>
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----
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Prelude> :t drop
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drop :: Int -> [a] -> [a]
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Prelude> drop 2 ["La", "Multi", "Ani","!"]
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["Ani","!"]
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Prelude>
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-----
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Prelude> :t dropWhile
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dropWhile :: (a -> Bool) -> [a] -> [a]
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Prelude> dropWhile (==0) [0,0,0,0,1,2,3,4,0,0,1,2]
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[1,2,3,4,0,0,1,2]
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Prelude>
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Prelude> :t elem
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elem :: Eq a => a -> [a] -> Bool
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Prelude> elem "!" ["La", "Multi", "Ani","!"]
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True
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Prelude> elem "2008" ["La", "Multi", "Ani","!"]
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False
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Prelude> elem "2000" ["La", "Multi", "Ani","!"]
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False
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Prelude>
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----
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Prelude> :t error
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error :: String -> a
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Prelude> error "Stop the train!"
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ERROR - Cannot find "show" function for:
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*** Expression : error "Stop the train!"
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*** Of type : a
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Prelude> error "Stop the train!" :Char
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ERROR - Undefined constructor function "Char"
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Prelude> error "Stop the train!" :: String
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"
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Program error: Stop the train!
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Prelude>
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----
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Prelude> :t exp
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exp :: Floating a => a -> a
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Prelude> exp 1
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2.71828
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Prelude>
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----
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Prelude> :t flip
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flip :: (a -> b -> c) -> b -> a -> c
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Prelude> (flip (>)) 1 2
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True
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Prelude>
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----
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Prelude> :t filter
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filter :: (a -> Bool) -> [a] -> [a]
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Prelude> filter (>2) [1,2,3,4,1]
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[3,4]
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Prelude>
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</haskell>
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----
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Pagina indexata la indexul [[Category:Ro]] [http://www.haskell.org/haskellwiki/Category:Ro Categories:Ro]
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----
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[http://www.haskell.org/haskellwiki/Ro/Haskell <= Inapoi la pagina principala Ro/Haskell. ]<br> <br>
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[http://www.haskell.org/haskellwiki/Intrebarile_incepatorului <'''-''' Inapoi la Intrebarile incepatorului Ro/Haskell. ]

Latest revision as of 15:19, 6 February 2021

Haskell - Un limbaj functional pur


Lista de functii des folosite, cu nume de la A la F. Pentru a vedea un exemplu de folosire (si tipul fiecarei functii) cautati numele ei mai jos pe pagina, cu Find-ul browser-ului.

abs - valoarea absoluta

all - predicatul e adevarat pe toata lista de argumente ?

and - conjunctie generalizata pe o lista de valori de tip Bool

any - exista o valoare pe lista care satisface predicatul (in engleza aceste intrebari se pun cu any)

atan - arctangenta

break - rupe o lista inaintea locului/elementului care satisface un predicat

ceiling - rotunjirea superioara la un intreg

chr - caracterul cu acel cod ascii, conversie numar - caracter

concat - concatenarea unui grup de liste , dat ca lista :) de liste

cos - cosinusul

digitToInt - transforma caracterul (daca e cifra) cifra in valoarea lui

div - impartirea intreaga

drop - arunca primele dintr-o lista

dropWhile - arunca primele care indeplinesc conditia 

         -- folositor la a  ajunge la primele elemente semnificative daca pui conditia invers

elem - apartine listei

error - genereaza eroare si poate avea orice tip, folositi-o deci oriunde exp - e(x)

flip - schimba ordinea argumentelor unei functii cu doua arg

filter - alege ce satisface predicatul, din lista data 

 
:t abs
abs :: Num a => a -> a

Prelude> abs -9
ERROR - Illegal Haskell 98 class constraint in inferred type
*** Expression : abs - 9
*** Type       : (Num a, Num (a -> a)) => a -> a

Prelude> abs (-9)
9
Prelude> abs (-9.3)
9.3
Prelude>             
----
Prelude> :t all
all :: (a -> Bool) -> [a] -> Bool
Prelude> all isDigit "12234678"
True
Prelude> all isDigit "danu"
False
Prelude>        
----
lse
Prelude> :t and
and :: [Bool] -> Bool
Prelude> and [True,True ,True]
True
Prelude> and [True,True ,True,False]
False
Prelude>        
----
Prelude> :t atan
atan :: Floating a => a -> a
Prelude>                     
Prelude> 4  * atan 1
3.14159
----
relude> :t break
break :: (a -> Bool) -> [a] -> ([a],[a])
Prelude> break isDigit "R2D2"
("R","2D2")
Prelude> break isDigit "3PO"
("","3PO")
Prelude>     
Prelude> break isSpace "La Multi Ani 2008!"
("La"," Multi Ani 2008!")
Prelude>       
Prelude> break (==0) [5,24,23,2,1,0,-1]
([5,24,23,2,1],[0,-1])
Prelude>                
----
Prelude> :t ceiling
ceiling :: (RealFrac a, Integral b) => a -> b
Prelude> ceiling 2.2
3
Prelude> ceiling 1.242
2
Prelude> ceiling 1.42
2
Prelude>              
----
Prelude> :t chr
chr :: Int -> Char

Prelude> chr 66
'B'
Prelude> chr 65
'A'
Prelude> chr 32
' '
Prelude>          
----
Prelude> :t concat
concat :: [[a]] -> [a]
Prelude> concat ["La", "Multi", "Ani","!"]
"LaMultiAni!"
Prelude>          
----
Prelude> :t cos
cos :: Floating a => a -> a
Prelude> cos 0
1.0
Prelude>     
----
relude> digitToInt "0"
ERROR - Type error in application
*** Expression     : digitToInt "0"
*** Term           : "0"
*** Type           : String
*** Does not match : Char

Prelude> digitToInt '0'
0
Prelude> digitToInt '1'
1
Prelude> digitToInt '2'
2
Prelude> digitToInt '3'
3
Prelude> digitToInt '4'
4
Prelude> digitToInt 'u'

Program error: Char.digitToInt: not a digit

Prelude>      
----
Prelude> :t div
div :: Integral a => a -> a -> a
Prelude> 10 `div` 3
3
Prelude>   
----
Prelude> :t drop
drop :: Int -> [a] -> [a]
Prelude> drop 2  ["La", "Multi", "Ani","!"]
["Ani","!"]
Prelude>               
-----
Prelude> :t dropWhile
dropWhile :: (a -> Bool) -> [a] -> [a]
Prelude> dropWhile  (==0) [0,0,0,0,1,2,3,4,0,0,1,2]
[1,2,3,4,0,0,1,2]
Prelude>          
Prelude> :t elem
elem :: Eq a => a -> [a] -> Bool
Prelude> elem "!"   ["La", "Multi", "Ani","!"]
True
Prelude> elem "2008"   ["La", "Multi", "Ani","!"]
False
Prelude> elem "2000"   ["La", "Multi", "Ani","!"]
False
Prelude>             
----
Prelude> :t error
error :: String -> a
Prelude> error "Stop the train!"
ERROR - Cannot find "show" function for:
*** Expression : error "Stop the train!"
*** Of type    : a

Prelude> error "Stop the train!" :Char
ERROR - Undefined constructor function "Char"
Prelude> error "Stop the train!" :: String
"
Program error: Stop the train!

Prelude>        
----
Prelude> :t exp
exp :: Floating a => a -> a
Prelude> exp 1
2.71828
Prelude>    
----
Prelude> :t flip
flip :: (a -> b -> c) -> b -> a -> c
Prelude> (flip (>)) 1 2
True
Prelude> 
----
Prelude> :t filter
filter :: (a -> Bool) -> [a] -> [a]
Prelude> filter (>2) [1,2,3,4,1]
[3,4]
Prelude>

Pagina indexata la indexul Categories:Ro

<= Inapoi la pagina principala Ro/Haskell.

<- Inapoi la Intrebarile incepatorului Ro/Haskell.

Retrieved from "https://wiki.haskell.org/index.php?title=Functii_din_Prelude,_A-F&oldid=63943"