[mhax]

Was it a 'functional programmers know the value of everything and the cost of nothing' kind of joke?

[dizzystar]

It filters for even.

Increments each element to odd.

Multiplies each number by 3 (each number is still odd)

Filters for evens then sums them.

Always returns zero.

[mhax]

but not one side effect!

[brailsafe]

Poetic.