import gleam/string pub type Error { OutOfRange } pub fn say(number: Int) -> Result(String, Error) { case number { 0 -> Ok("zero") _ if number < 0 -> Error(OutOfRange) _ if number >= 1_000_000_000_000 -> Error(OutOfRange) _ -> number |> do_say |> string.replace(" ", " ") |> string.trim() |> Ok } } const billion = 1_000_000_000 const million = 1_000_000 const thousand = 1000 const hundred = 100 fn do_say(number: Int) -> String { case number { _ if number >= billion -> { let billions = number / billion let rest = number % billion do_say(billions) <> " billion " <> do_say(rest) } _ if number >= million -> { let millions = number / million let rest = number % million do_say(millions) <> " million " <> do_say(rest) } _ if number >= thousand -> { let thousands = number / thousand let rest = number % thousand do_say(thousands) <> " thousand " <> do_say(rest) } _ if number >= hundred -> { let hundreds = number / hundred let rest = number % hundred do_say(hundreds) <> " hundred " <> do_say(rest) } _ if number >= 20 -> { let num_tens = number / 10 let rest = number % 10 case rest { 0 -> tens(num_tens) _ -> tens(num_tens) <> "-" <> ones(rest) } } _ -> ones(number) } } fn ones(number: Int) -> String { case number { 0 -> "" 1 -> "one" 2 -> "two" 3 -> "three" 4 -> "four" 5 -> "five" 6 -> "six" 7 -> "seven" 8 -> "eight" 9 -> "nine" 10 -> "ten" 11 -> "eleven" 12 -> "twelve" 13 -> "thirteen" 14 -> "fourteen" 15 -> "fifteen" 16 -> "sixteen" 17 -> "seventeen" 18 -> "eighteen" _19 -> "nineteen" } } fn tens(number: Int) -> String { case number { 2 -> "twenty" 3 -> "thirty" 4 -> "forty" 5 -> "fifty" 6 -> "sixty" 7 -> "seventy" 8 -> "eighty" _9 -> "ninety" } }