A "map" can be a function (applied to a (single) value). Got it. Thanks, Michael --- On Fri, 8/27/10, Ivan Lazar Miljenovic <ivan.miljenovic@gmail.com> wrote: From: Ivan Lazar Miljenovic <ivan.miljenovic@gmail.com> Subject: Re: [Haskell-cafe] On to applicative To: "michael rice" <nowgate@yahoo.com> Cc: haskell-cafe@haskell.org Date: Friday, August 27, 2010, 8:46 PM On 28 August 2010 10:38, michael rice <nowgate@yahoo.com> wrote:
fmap seems oddly named because no "mapping" takes place, except in the fourth example, where the map is "passed in." Just sayin'.
*ahem* http://en.wikipedia.org/wiki/Map_%28mathematics%29
Prelude Control.Monad Control.Applicative Data.Char> fmap toUpper getLine
<interactive>:1:13: Couldn't match expected type `Char' against inferred type `[Char]' Expected type: IO Char Inferred type: IO String In the second argument of `fmap', namely `getLine' In the expression: fmap toUpper getLine
Right; this is because the fmap only gets the "Char -> Char" function inside the IO; but since it's "IO String" rather than "IO Char", this doesn't type-check. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com