-- fibonacci function with cache
-- very inefficient fibonacci function
function fib(n)
N=N+1
if n<2 then
return n
else
return fib(n-1)+fib(n-2)
end
end
-- a general-purpose value cache
function cache(f)
local c={}
return function (x)
local y=c[x]
if not y then
y=f(x)
c[x]=y
end
return y
end
end
cached_fib = cache(fib)
N=0
assert(fib(24) == 46368)
N=0
assert(cached_fib(24) == 46368)