[Haskell-beginners] numerical integration over lists

[Thomas Engel]

Hello,

I have two list (one with x values, the other with y values)
What I want to do is a numercial integration according the following formula:

Result x2 = Result x1 + ((y(x1) + y(x2))/2) * (x2 -x1)

and put the result in another list.

below my first try:

integriereListe::(a)->(a)->(a)
integriereListe [][]  = [0.0]
integriereListe (x:xs) (y:ys)   = ((y - y2) /2) * (x2 -x)
                                  where
                                  x2 = head xs
                                  y2 = head ys    

but I got the failure

 Couldn't match type `[t0]' with `[[t0]]'
    In the pattern: y : ys
    In an equation for `integriereListe':
        integriereListe (x : xs) (y : ys)
          = ((y - y2) / 2) * (x2 - x)
          where
              x2 = head xs
              y2 = head ys
                     

another problem is how get the result  x1 (see above)

any hints are welcome.

Thomas