Why am I getting a parse error on "a b c d"?

computeNumbers :: Float -> Int -> Int -> Float -> Float 
computerNumbers (a b c d) = ((pi * a/2 ^2) * 0.002   (((pi * a/2 ^2) * 0.001) * b)   c * 0.55) * 1.5   (if d > 0 then d * 0.9 else d)

I have tried everything from deleting every space between words to make sure that I did not use TAB by mistake and rearrange the brackets. Nothing worked so far.

CodePudding user response：

Get rid of the parentheses entirely.

Without the parens you are binding the names to the four arguments. With the parens you are matching a single argument with a pattern that does not match a Float.