Valid Phone Number

[evantianx]

Description:

Write a function that accepts a string, and returns true if it is in the form of a phone number. Assume that any integer from 0-9 in any of the spots will produce a valid phone number.

Only worry about the following format: (123) 456-7890 (don't forget the space after the close parentheses)

Examples:

validPhoneNumber("(123) 456-7890")  =>  returns true
validPhoneNumber("(1111)555 2345")  => returns false
validPhoneNumber("(098) 123 4567")  => returns false

[evantianx]

Solutions

import Data.Char

validPhoneNumber :: String -> Bool
validPhoneNumber str = "(000) 000-0000" == map trans str
  where trans ch 
    | isDigit ch = '0'
    | otherwise = ch