CODEWITHSUNDEEP
haskellif-statementlogicconditional-statements
eXistanCe
eXistanCe

Reputation: 735

Haskell multiple conditions of If

I am having problems with the following exercise:

Write a function that receives three Ints and sums them if they are all positive and returns 0 (zero) otherwise.

What I have done is the following:

sum' :: int -> int -> int -> int
sum' x y z = if x >= 0, y >= 0, z >= 0 then x+y+z else 0

I don't know how to make multiple conditions on an if, not sure if this is done with logical "connectors" (like || or && in Java) or if it is done in a similar way to the code I wrote.

Upvotes: 2

Views: 14849

Answers (2)

fgv
fgv

Reputation: 835

Or using guards, which would make it look almost exactly like the human version of the definition:

sum' :: Int -> Int -> Int -> Int
sum' x y z 
    | x >= 0 && y >= 0 && z >= 0 = x+y+z
    | otherwise = 0

On a side note, always remember that types start with a capital letter. In your case, your type signature should use "Int" instead of "int".

I hope this helps.

Upvotes: 4

user1804599
user1804599

Reputation:

It can be done in multiple ways.

For example, using &&:

sum' :: Int -> Int -> Int -> Int
sum' x y z = if x >= 0 && y >= 0 && z >= 0 then x+y+z else 0

Or using all and a list:

sum' :: Int -> Int -> Int -> Int
sum' x y z = if all (>= 0) xs then sum xs else 0
    where xs = [x, y, z]

Upvotes: 9

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