fizzbuzz_pm.rb

# typed: ignore
# Ruby 2.7 (Pattern Matching)

require 'sorbet-runtime'

class FizzBuzz
    extend T::Sig

    sig {params(n: Integer).void}
    def self.check_number(n)
        if n <= 0 then raise ArgumentError end
    end

    sig {params(n: Integer).returns(T::Boolean)}
    def self.is_fizz(n)
        check_number(n)
        n % 3 == 0
    end

    sig {params(n: Integer).returns(T::Boolean)}
    def self.is_buzz(n)
        check_number(n)
        n % 5 == 0
    end

    sig {params(n: Integer).returns(T::Array[T.any(Symbol, Integer)])}
    def self.number_as(n)
        case [is_fizz(n), is_buzz(n)]
        in [true, true]
            [:FizzBuzz, n]
        in [true, false]
            [:Fizz, n]
        in [false, true]
            [:Buzz, n]
        else
            [:Number, n]
        end
    end

    sig {params(fz: T::Array[T.any(Symbol, Integer)]).returns(String)}
    def self.to_str(fz)
        case fz
        in [:Number, n]
            n.to_s
        in [s, _]
            s.to_s
        else
            raise ArgumentError
        end
    end

    sig {void}
    def self.main()
        puts (1..100)
            .map(&(method(:number_as) >> method(:to_str)))
            .zip((1..100).to_a)
            .map{|fzs, n| "#{n} => #{fzs}"}
    end
end

if __FILE__ == $PROGRAM_NAME
    FizzBuzz.main()
end