Dear Haskell Fans, I'm afraid that I'm a bit dumb but I'm somewhat
stuck.
Can someone give me a hand on this problem
I wrote this code to solve SOE, exc 5.1.
import Shape
triangleArea :: [Vertex] -> Float
triangleArea (v1:v2:v3:_) = let a = distBetween v1 v2
b = distBetween v2 v3
c = distBetween v3 v1
s = 0.5 * (a + b + c)
in sqrt (s * (s-a) *(s-b) * (s-c))
triangleArea _ = 0
o_array :: Shape -> Float
o_array (Polygon (v1:vs)) =
let ph = phelp vs
in
foldr (+) 0.0 (map triangleArea ph)
where phelp :: [Vertex] -> [[Vertex]]
phelp (v2:v3:vs) = (v1:v2:v3:[]):phelp (v3:vs)
phelp _ = []
what I want is to replace the recursive phelp function with a function
using higher order functions.
My base idea is splitting up List of Vertices into a list of exactly
three vertices calculating that area and adding them all.
BTW, I do not like the above solution anyway. It's too bulky. So if one has
another idea on how to tackle it, I would be very thankful to some
hint.
Best regards
Friedrich
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