Contents

module Phone (number) where
import Data.Char (isDigit)

number :: String -> Maybe String
number input = clean input >>= check

check :: String -> Maybe String
check ('0':_) = Nothing
check ('1':_) = Nothing
check (_:_:_:'0':_) = Nothing
check (_:_:_:'1':_) = Nothing
check s = Just s

clean :: String -> Maybe String
clean input
  | len == 10 = Just digits
  | len == 11 && head digits == '1' = Just $ tail digits
  | otherwise = Nothing
  where digits = filter isDigit input
        len = length digits

Version data entries

229 entries across 229 versions & 1 rubygems

Version	Path
trackler-2.2.1.180	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.179	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.178	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.177	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.176	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.175	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.174	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.173	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.172	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.171	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.170	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.169	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.167	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.166	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.165	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.164	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.163	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.162	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.161	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs
trackler-2.2.1.160	tracks/haskell/exercises/phone-number/examples/success-standard/src/Phone.hs