Haskell version:<p><pre><code> import Data.Number.Fixed
pis :: [Fixed Prec50]
pis = map termToPi $ iterate update (1, 1/(sqrt 2), 1/4, 1)
where update (a,b,t,p) = (a',b',t',p')
where a' = (a+b)/2
b' = sqrt(a*b)
t' = t - p * sqr(a - a')
p' = 2 * p
termToPi (a,b,t,_) = sqr(a + b) / (4*t)
sqr x = x*x
main = putStrLn . show $ pis !! 20
-- 3.14159265358979323846264338327950288419716939937583
</code></pre>
IMHO that was cleaner and easier than the Clojure code. I didn't really get the bindings thing.<p>Edit: Out of curiosity I checked with Debug.Trace to see how it runs, and termToPi only gets called once for the term that was requested, even though I said "map termToPi". Fun!