[Haskell-cafe] On to applicative
michael rice
nowgate at yahoo.com
Fri Aug 27 20:38:50 EDT 2010
fmap seems oddly named because no "mapping" takes place, except in the fourth example, where the map is "passed in." Just sayin'.
Michael
1)
Prelude Control.Monad Control.Applicative> fmap (++ "abc") getLine
xyz
"xyzabc"
2)
Prelude Control.Monad Control.Applicative Data.Char Data.String> fmap (splitAt 3) getLine
qwertyuio
("qwe","rtyuio")
3)
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
4)
Prelude Control.Monad Control.Applicative Data.Char Data.String> fmap (map toUpper) getLine
qwertyuio
"QWERTYUIO"
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