Hmm, if the mutation is just purely sequential, it's just an implementation detail. Ideally, you would express the solution at a high-level, close to the mathematics and without mentioning mutation, and have your code optimized to the mutable version for you. After all, it's just a series of transformations over some data--exactly what functional programming is!
This sounds like an appeal to a "sufficiently smart compiler", but really we're already part of the way there with things like vector and stream fusion in Haskell. I know that some of Haskell's vector functions are already smart enough to run in-place if they can get away with it.
This sounds like an appeal to a "sufficiently smart compiler", but really we're already part of the way there with things like vector and stream fusion in Haskell. I know that some of Haskell's vector functions are already smart enough to run in-place if they can get away with it.