[Rio-pm] [Golf] Função drop Haskell

[breno]

Nilson, o final deveria dizer "mas é igual à versão do Nilson". Como
eu fiz um monte de edições e contagens, acabou q foi enviado sem e eu
nao percebi. O crédito e a menor tacada ainda são seus :-)

[]s

-b

2010/2/3 Nilson Santos Figueiredo Jr. <acid06 em gmail.com>:
> Breno,
>
> Essa que você mandou é exatamente igual a minha anterior, mas ao invés
> de $a,$b eu uso $n,$w.
> Tem 65 chars fora e 55 dentro. Eu estava contando tudo.
>
> Mas essa tem um problema que retorna undef em alguns casos. Aí o
> Mantovani que tem que falar se é certo ou não.
>
> -Nilson
>
> 2010/2/3 breno <breno em rio.pm.org>:
>> fernando, nao pode funcionar pra valores negativos, vai entender :-)
>>
>> acredito que assim funcione:
>>
>> sub drop{($a,$b)=@_;$a=0if$a<0;ref$b?@$b[$a..$#{$b}]:substr$b,$a}
>>
>> 55 chars (dentro da sub).
>>
>>
>>
>> 2010/2/3 Fernando Oliveira <fernandocorrea em gmail.com>:
>>> 54:
>>>
>>> sub drop{($a,$b)=@_;ref$b?@$b[$a..$#{$b}]:substr$b,$a}
>>>
>>> Just another Perl Hacker,
>>> Fernando (SmokeMachine)
>>> http://perl-e.org
>>>
>>>
>>>
>>> Em 3 de fevereiro de 2010 17:54, Nilson Santos Figueiredo Jr.
>>> <acid06 em gmail.com> escreveu:
>>>>
>>>> Pronto, 80 caracteres (sem strict).
>>>> Estou satisfeito, agora é com vocês:
>>>>
>>>> sub
>>>> drop{($n,$w)=@_;$n=0if$n<0;ref$w?@$w[$n..$#{$w}]:$n>length$w?'':substr$w,$n}
>>>>
>>>> -Nilson
>>>>
>>>> 2010/2/3 Nilson Santos Figueiredo Jr. <acid06 em gmail.com>:
>>>> > Melhorando a minha solução anterior, 85 caracteres (83 tirando o my):
>>>> >
>>>> > sub drop{my($n,$w)=@_;$n=0
>>>> > if$n<0;ref$w?@$w[$n..$#{$w}]:$n>length$w?'':substr($w,$n)}
>>>> >
>>>> > -Nilson
>>>> >
>>>> > 2010/2/3 Nilson Santos Figueiredo Jr. <acid06 em gmail.com>:
>>>> >> Uma solução, warnings and strict compliant:
>>>> >>
>>>> >> sub drop {
>>>> >>    my ($n, $w) = @_;
>>>> >>    $n = 0 if $n < 0;
>>>> >>    return ( $n > length $w ? '' : substr($w,$n) ) if !ref $w;
>>>> >>    @$w[$n..$#{$w}];
>>>> >> }
>>>> >>
>>>> >> Se colocar tudo em uma linha:
>>>> >>
>>>> >> sub drop{my($n,$w)=@_;$n=0
>>>> >> if$n<0;return($n>length$w?'':substr($w,$n))if!ref$w;@$w[$n..$#{$w}];}
>>>> >>
>>>> >> 96 caracteres. Deve dar pra melhorar bastante ainda. Se tirar o "my"
>>>> >> pra deixar de ser strict compliant, cai pra 94.
>>>> >>
>>>> >> -Nilson
>>>> >>
>>>> >> 2010/2/3 Daniel de Oliveira Mantovani
>>>> >> <daniel.oliveira.mantovani em gmail.com>:
>>>> >>> Olá pessoal, o desafio envolve a função drop do Haskell:
>>>> >>>
>>>> >>> <haskell>
>>>> >>> ghci> myDrop 2 "foobar"
>>>> >>> "obar"
>>>> >>> ghci> myDrop 4 "foobar"
>>>> >>> "ar"
>>>> >>> ghci> myDrop 4 [1,2]
>>>> >>> []
>>>> >>> ghci> myDrop 0 [1,2]
>>>> >>> [1,2]
>>>> >>> ghci> myDrop 7 []
>>>> >>> []
>>>> >>> ghci> myDrop (-2) "foo"
>>>> >>> "foo"
>>>> >>> </haskell>
>>>> >>>
>>>> >>> Eu fiz em Perl, para ficar claro:
>>>> >>>
>>>> >>> <perl>
>>>> >>> sub drop {
>>>> >>>    my ( $n, $xs ) = @_;
>>>> >>>    if ( ref $_[1] ne 'ARRAY' ) {
>>>> >>>        $n <= 0 ? return $_[1] : return substr( $_[1], $n );
>>>> >>>    }
>>>> >>>    if ( $n <= 0 || !@_ ) {
>>>> >>>        return @{$xs};
>>>> >>>    }
>>>> >>>    else {
>>>> >>>        shift @{$xs};
>>>> >>>        drop( ( $n - 1 ), $xs );
>>>> >>>    }
>>>> >>> }
>>>> >>> </perl>
>>>> >>>
>>>> >>> Exemplos:
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(3,[1,2,3,4,5,6])'
>>>> >>> 4
>>>> >>> 5
>>>> >>> 6
>>>> >>>
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(1,"ofernandoagoragolf")'
>>>> >>> fernandoagoragolf
>>>> >>>
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(2,["mantovani","garu","fernando","blabos"])'
>>>> >>> fernando
>>>> >>> blabos
>>>> >>>
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(-1,["mantovani","garu","fernando","blabos"])'
>>>> >>> mantovani
>>>> >>> garu
>>>> >>> fernando
>>>> >>> blabos
>>>> >>>
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(-1,"mantovani")'
>>>> >>> mantovani
>>>> >>>
>>>> >>> mantovani em mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>> >>> $_ for drop(10,"mantovani")'
>>>> >>>
>>>> >>> --
>>>> >>> "If you’ve never written anything thoughtful, then you’ve never had
>>>> >>> any difficult, important, or interesting thoughts. That’s the secret:
>>>> >>> people who don’t write, are people who don’t think."
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>>>> >>
>>>> >
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