Is there a functional algorithm which is faster than an imperative one?

I'm searching for an algorithm (or an argument of such an algorithm) in functional style which is faster than an imperative one.

I like functional code because it's expressive and mostly easier to read than it's imperative pendants. But I also know that this expressiveness can cost runtime overhead. Not always due to techniques like tail recursion - but often they are slower.

While programming I don't think about runtime costs of functional code because nowadays PCs are very fast and development time is more expensive than runtime. Furthermore for me readability is more important than performance. Nevertheless my programs are fast enough so I rarely need to solve a problem in an imperative way.

There are some algorithms which in practice should be implemented in an imperative style (like sorting algorithms) otherwise in most cases they are too slow or requires lots of memory. In contrast due to techniques like pattern matching a whole program like a parser written in an functional language may be much faster than one written in an imperative language because of the possibility of compilers to optimize the code.

But are there any algorithms which are faster in a functional style or are there possibilities to setting up arguments of such an algorithm?

A simple reasoning. I don't vouch for terminology, but it seems to make sense.

• A functional program, to be executed, will need to be transformed into some set of machine instructions.
• All machines (I've heard of) are imperative.
• Thus, for every functional program, there's an imperative program (roughly speaking, in assembler language), equivalent to it.

So, you'll probably have to be satisfied with 'expressiveness', until we get 'functional computers'.