Help with Haskell Program

Question

Im learning Haskell and was wondering if anyone could tell me how to write a program called say triangle which takes a number and adds all previous numbers down to 0.

EG: triangle 4 = 4 3 2 1 0 so triangle 4 = 10?

Any idea's thanks.

Answer 1

My Haskell syntax is really rusty so I will leave the syntax out but basically you need to store the total and add to it the decrementing number e.g.

triangle 4

value = 4;

sum = 0;

while(value >= 0)

{

    sum = sum + value;

    value = value - 1;

}

Sorry for lack on Haskell syntax but there should be examples on the net