[Rio-pm] [Golf] Função drop Haskell

[Nilson Santos Figueiredo Jr.]

Eu tenho certeza que vai dar pra alguém melhorar, ainda tá grande.
Mas se eu ficar mais tempo aqui tentando... vou ter meus dias inteiros
pra ficar brincando de Golf ao invés de ter um trabalho. ;-)

-Nilson

2010/2/3 breno <breno at rio.pm.org>:
> 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 at 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 at 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,$a}
>>>
>>> 55 chars (dentro da sub).
>>>
>>>
>>>
>>> 2010/2/3 Fernando Oliveira <fernandocorrea at gmail.com>:
>>>> 54:
>>>>
>>>> sub drop{($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 at 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,$n}
>>>>>
>>>>> -Nilson
>>>>>
>>>>> 2010/2/3 Nilson Santos Figueiredo Jr. <acid06 at gmail.com>:
>>>>> > Melhorando a minha solução anterior, 85 caracteres (83 tirando o my):
>>>>> >
>>>>> > sub drop{my($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 at 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 at 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 ), $xs );
>>>>> >>>    }
>>>>> >>> }
>>>>> >>> </perl>
>>>>> >>>
>>>>> >>> Exemplos:
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>>> >>> $_ for drop(3,[1,2,3,4,5,6])'
>>>>> >>> 4
>>>>> >>> 5
>>>>> >>> 6
>>>>> >>>
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>>> >>> $_ for drop(1,"ofernandoagoragolf")'
>>>>> >>> fernandoagoragolf
>>>>> >>>
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>>> >>> $_ for drop(2,["mantovani","garu","fernando","blabos"])'
>>>>> >>> fernando
>>>>> >>> blabos
>>>>> >>>
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>>> >>> $_ for drop(-1,["mantovani","garu","fernando","blabos"])'
>>>>> >>> mantovani
>>>>> >>> garu
>>>>> >>> fernando
>>>>> >>> blabos
>>>>> >>>
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ perl -MHaskell -E 'say
>>>>> >>> $_ for drop(-1,"mantovani")'
>>>>> >>> mantovani
>>>>> >>>
>>>>> >>> mantovani at mantovani-desktop:~/Perl/Funcional$ 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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