Pascal Triangle Find position x, y with Haskell function

Question

I want to get 2 integers from an input like pascal 2 1. This input should be 2, because the list starts with x and y = 0. Also pos must be <= row and i don't want to use guards. My code looks like this:

pascal :: Int -> Int -> Int
pascal row pos
        if row == 0 || pos == 0 then "1" 
        else if row > pos then error "Invalid input." 
        else (pascal (row-1) (pos-1)) + (pascal (row-1) (pos))

Error code:

Unexpected if expression in function application:
if row == 0 || pos == 0 then
        "1"
    else
        if row > pos then
            error "Invalid input."
        else
            (pascal (row - 1) (pos - 1)) + (pascal (row - 1) (pos))
You could write it with parentheses
Or perhaps you meant to enable BlockArguments?

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. — Community, Nov 16 '21 at 11:17
Hi Plex, what is your question? It looks like you got an compile error and you don't understand why. You should state your question explicitly. — Martin Böschen, Nov 16 '21 at 11:18

score 0 · Answer 1 · answered Nov 14 '21 at 08:53

pascal :: Int -> Int -> Int
pascal row pos = 
        if row == 0 || pos == 0 then 1 
        else if row > pos then error "Invalid input." 
        else (pascal (row-1) (pos-1)) + (pascal (row-1) (pos))

To get rid of that error you just need to add an =, which you probably just forgot. But this is really bad style in Haskell. This code begs for guards.

Pascal Triangle Find position x, y with Haskell function

1 Answers1