Seven Languages in Seven Weeks - Io. fib.io: Fibonacci number, using recursion and loops; divide_by_zero.io: Change built-in behavior so that divide by zero returns 0. sum_matrix.io: Sum values in a two-dimensional list; my_average.io: Implement slot method myAverage on list primitive which returns the average of a list and throws an exception i…

divide_by_zero.io

oldDivision := Number getSlot("/")
Number / := method( a,
if( a <= 0, 0, self oldDivision( a ) )
)
 
writeln( 1 / 2 ) # prints "0.5"
writeln( 1 / 1 ) # prints "1"
writeln( 1 / 0 ) # prints "0"

fib.io

# implemented with recursion
fib := method( i,
    if(i > 2, fib(i-2) + fib(i-1), 1)
)

# implemented with loops
fib2 := method( i,
    a := 1; b := 1; c := 0; j := 1;
    while(j < i,
        c = a + b; a = b;  b = c; j = j + 1;
    );
    a
)

fib(6) println # prints "8"

fib2(7) println # prints "13"

my_average.io

List myAverage := method(
    if(
        self size == 0,
        Exception raise("The list is empty!"),
        total := 0;
        self foreach(i, v,
            total = total + v
        );
        total / self size
    )
)

newList := list(1,2,3,4,5,6,7)
newList myAverage println

newList2 := list()
newList2 myAverage println

sum_matrix.io

sumMatrix := method( list,
    total := 0;
    list foreach( i, v,
        v foreach( j, w,
            w println;
            total = total + w
        )
    )
)

dummy := list(
    list(1,2,3),
    list(1,2,3),
    list(1,2,3)
)

sumMatrix( dummy ) println

trix.io

Trix := Object clone

Trix dim := method( x, y,
    self thislist := list()
    for(i, 1, y,
        self thislist append(
            subList := list();
            for(j, 1, x,
                subList append(nil)
            );
            subList
        )
    )
)

Trix set := method( x, y, val,
    yList := thislist at(y - 1);
    yList atPut(x - 1, val)
)

Trix get := method( x, y, val,
    yList := thislist at(y - 1);
    yList at(x - 1)
)

Trix println := method(
    thislist println
)

trix := Trix clone

trix dim(3,4)

trix println

trix set(2, 1, 7)
trix set(1, 3, 5)

trix println

trix get(1, 3) println