Well, yes. But that's the same argument for fine-grained control which people have been making ever since the move away from assembler to high level languages.

There are (nearly) always cases were the higher-level approach suffers in performance, but the gains in expressiveness are worthwhile. (And often the compiler/interpreter can guess better than the programmer - note that hand-coded assembler these days is often slower than well-compiled C, because of x86 architectural issues).

As another example - purely functional code has no side effects and so the compiler is permitted to parallelize it across multiple CPUs or cores. One can argue that one would prefer the control of explicit threads and locks, but the effort and error rate in doing so is likely to be high.

Whether current compilers have all these features or not (I'm not sure), fundamentally, functional code is more amenable to aggressive optimisation and parallelisation - as well as allowing high levels of expressiveness.

Imagine a perl6 pragma which told parrot that the enclosing lexical block contained no side-effects (or a code analysis phase which determined the same thing) and allowed the loop in the block to automagically run on all 4 cores of your 2007 CPU.

In reply to Re^3: a better fibonacci subroutine by jbert
in thread a better fibonacci subroutine by apotheon

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