[Haskell-cafe] Re: Keys and Maps [Was: Re: I just don't get it (data structures and OO)]

Albert Y. C. Lai trebla at vex.net
Thu Jun 7 18:15:22 EDT 2007

Justin Bailey wrote:
> On 6/7/07, Grzegorz <grzegorz.chrupala at computing.dcu.ie> wrote:
>> All this hard work for something that in a lesser language would be the
>> unimpressive:  universe["Milky Way"]["Sun"] ;-P
> Well, if you want to get picky there is the '!' operator defined in 
> Data.Map:
>> universe ! "Milky Way" ! "Sun"

I second that. I particularly like the elimination of ]'s. We certainly 
need some symbol to separate the map and the key; but we do really need 
to also mark "here be the end of the key"?

(Evidently, this carries over to array indexing and function application 
too, i.e., a!!i vs a[i], f$x or f x vs f(x).)

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