NumberName.hs

--For Euler Problem 17
onesNames = ["","One","Two","Three","Four","Five","Six","Seven","Eight","Nine"]
teenNames = ["Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"]
tensNames = ["", "","Twenty","Thirty","Forty","Fifty","Sisty","Seventy","Eighty","Ninety"]

numberToName x = (thousands x) ++ (hundreds x) ++ (addAnd x) ++ (tens x) ++ (ones x)

thousands x = 
    if  digit > 0
        then (onesNames !! digit) ++ "Thousand"
        else ""
    where
        digit = mod (x `div` 1000) (10)
        
hundreds x = 
    if  digit > 0
        then (onesNames !! digit) ++ "Hundred"
        else ""
    where
        digit = mod (x `div` 100) (10)
        
addAnd x = 
    if  ((div x 100) > 0) && ((mod x 100) > 0)
        then "And"
        else ""
    where
        digit = mod (x `div` 100) (10)
        
tens x = 
    if  digit > 0
        then 
            if digit >= 2
                then tensNames !! digit
                else teenNames !! (mod x 10)
        else ""
    where
        digit = mod (x `div` 10) (10)
        
ones x = 
    if ((mod x 10) > 0) && ((div (mod x 100) 10) /= 1)
        then onesNames !! (mod x 10)
        else ""