La ce folosim operatorul !! (dublu semn de exclamare) ?
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Este folosit pentru a extrage al n-lea element dintr-o lista, n fiind numar intreg.
Aruncati o privire aici:
Prelude> :t (!!)
(!!) :: [a] -> Int -> a
Prelude> (!!) [1,2,3,5] 0
1
Prelude> (!!) [1,2,3,5] 1
2
Prelude> (!!) [1,2,3,5] 2
3
Prelude> (!!) [1,2,3,5] 3
5
Prelude> (!!) [1,2,3,5] 4
Program error: Prelude.!!: index too large <= Inapoi la pagina principala Ro/Haskell