codepad
[
create a new paste
]
login
|
about
Language:
C
C++
D
Haskell
Lua
OCaml
PHP
Perl
Plain Text
Python
Ruby
Scheme
Tcl
-- $setup -- >>> import Test.QuickCheck -- >>> import Control.Applicative -- | maybeReadPositiveInt Try to parse a positive Int -- Can be done point-free (and it's probably funnier this way). -- -- Examples: -- -- prop> (==) <$> Just <*> maybeReadPositiveInt . show $ getNonNegative x -- -- prop> Nothing == (maybeReadPositiveInt . show . negate . getPositive $ x) -- -- >>> maybeReadPositiveInt "foo" -- Nothing -- -- >>> maybeReadPositiveInt "12 " -- Nothing maybeReadPositiveInt :: String -> Maybe Int maybeReadPositiveInt = undefined main = do print $ maybeReadPositiveInt "12" -- Just 12 print $ maybeReadPositiveInt "-12" -- Nothing print $ maybeReadPositiveInt "12 a" -- Nothing print $ maybeReadPositiveInt "12 " -- Nothing
Private
[
?
]
Run code
Submit