module tests\CommonFunctions exports
    factorial,
    fibonacci,
    bmiTell,
    nonLinearTupleTest,
    nonLinearListTest,
    nonLinearHeadTailsTest,
    nonLinearAsSequenceOneTest,
    nonLinearAsSequenceTwoTest,
    countdown,
    read_all_lines,
    print_sequence,
    raise_error
    as

    #factorial 1 = 1
    #factorial n = n * factorial (n - 1)

    # A tail recursive function to calculate factorial
    factTR 0 a = a
    factTR n a = factTR (n - 1) (n * a)

    # A wrapper over factTR
    factorial n = factTR n 1

    fibonacci 0 = 0
    fibonacci 1 = 1
    fibonacci n = fibonacci (n - 1) + fibonacci (n - 2)

    bmiTell bmi
        | bmi <= 18.5 = "You're underweight, you emo, you!"
        | bmi <= 25.0 = "You're supposedly normal. Pffft, I bet you're ugly!"
        | bmi <= 30.0 = "You're fat! Lose some weight, fatty!"
        | true        = "You're a whale, congratulations!"

    nonLinearTupleTest (arg, _) (_, arg)       = arg
    nonLinearTupleTest (argOne, _) (_, argTwo) = argOne + argTwo

    nonLinearListTest [arg, _] [_, arg]       = arg
    nonLinearListTest [argOne, _] [_, argTwo] = argOne + argTwo

    nonLinearHeadTailsTest head -| _ head -| _       = head
    nonLinearHeadTailsTest headOne -| _ headTwo -| _ = headOne + headTwo

    nonLinearAsSequenceOneTest seqOne@(head -| _) seqTwo@(head -| _)       = head
    nonLinearAsSequenceOneTest seqOne@(headOne -| _) seqTwo@(headTwo -| _) = headOne + headTwo

    nonLinearAsSequenceTwoTest seq@(headOne -| _) seq@(headTwo -| _)       = headOne
    nonLinearAsSequenceTwoTest seqOne@(headOne -| _) seqTwo@(headTwo -| _) = headOne + headTwo

    countdown n
        | n < 1 = 0
    countdown n = countdown (n - 1)


    read_all_lines file = read_lines file 0

    read_lines file acc =
        case File::read_line file of
            (:ok, _, new_file)  -> read_lines new_file (acc + 1)
            :eof                -> acc
        end

    print_sequence []     = ""
    print_sequence h -| t =
        do
            IO::println h
            print_sequence t
        end


    raise_error = raise :test_error "testing error"
end