# 1) Fibanacci by recursion (fibr) and loop (fibl)
fibr := method(num,
    if (num < 1,
        return 0,
        if (num == 1,
            return 1,
            prev := fibr(num - 1) ;
                prev_prev := fibr(num - 2) ;
                return prev + prev_prev
        )
    )
)

"fibr(9) = " print
fibr(9) println
"fibr(4) = " print
fibr(4) println
"fibr(1) = " print
fibr(1) println


fibl := method(num,
    if (num < 1, return 0)
    if (num == 1, return 1)
    prev := 1
    prev_prev := 0
    val := 0    
    for(i, 2, num,
        val = prev + prev_prev
        prev_prev = prev
        prev = val
    )
    return val
)

"fibl(9) = " print
fibl(9) println
"fibl(4) = " print
fibl(4) println
"fibl(1) = " print
fibl(1) println


# 2) Changing "/" operator to return 0 for a zero denominator
# Operators are just messages on objects, so "/" is the message to override
# and it must be on the object type Number
Number defaultDivide := Number getSlot("/")
Number / := method(denom,
    if (denom == 0,
        return 0,
        return self defaultDivide(denom))
)
(4 / 2) println
(4 / 0) println


# 3) Add up numbers in a 2D array
arr := list(
    list(1, 2, 3),
    list(4, 5, 6),
    list(7, 8, 9)
)

add2D := method(arr,
    sum := 0
    # A "reduce()" method would be nice, but KISS for now and foreach all the things
    arr foreach(dimension, dimension foreach(val, sum = sum + val))
    return sum
)

add2D(arr) println


# 4) Add myAverage to average numbers in a list
List myAverage := method(
    sum := 0
    self foreach(val, if (val proto == Number,
                          sum = sum + val,
                          Exception raise("Non-object found in list"))
                )
    return sum / self size
)

list(1, 2, 3) myAverage println
# This will exception - run at the end!
# list(1, 2, 3, "foo") myAverage
# With default behaviour then this could divide by zero (unless we'd been defensive coding)
# But we're in the same file as our custom "/", so we should get zero
list() myAverage println


list(1, 2, 3, "foo") myAverage