[Haskell-beginners] mayBe stuck
prad at towardsfreedom.com
Thu Aug 5 18:22:35 EDT 2010
i'm trying to create my own split function with % as delimiter.
so i have
eqD = (=='%')
let s = "zaoeu%aeuasnt%staashaeu%nthdanoe%nthd"
putStrLn $ show $ brS (findIndex eqD s) s
to a function brS:
brS i ss
| isNothing i = ss
| otherwise = (take i ss) : (brS newIndex newStr)
newIndex = findIndex eqD newStr
newStr = drop (i+1) ss
but get the following error:
Couldn't match expected type `Maybe a' against inferred type `Int'
In the first argument of `isNothing', namely `i'
In the expression: isNothing i :: mayBe a
In a stmt of a pattern guard for
the definition of `brS':
isNothing i :: mayBe a
my understanding is that i need the isNothing because findIndex will
return Just Int or Nothing.
however, i'm not sure how to resolve what seems to me to be an issue
between a Maybe and an Int.
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