Hello,
http://blog.wolframalpha.com/2009/05/01/the-secret-behind-the-computational-engine-in-wolframalpha/ <<< this is obviously a Wolfram Inc. blog so maybe not totally objective ... but here is a snippet that speaks in Haskell's favor:
As a result, the five million lines of Mathematica code that make up Wolfram|Alpha are equivalent to many tens of millions of lines of code in a lower-level language like C, Java, or Python.