Copying data is wasteful, mutating data is dangerous
As a game developer working in managed languages (aka Unity/C#) this problem is one of my biggest headaches. I was hoping the article would provide divine insight, unfortunately the recommend solution doesn't really solve the problem (as I see it).Whilst 2n array alloc is better than 3n, both are creating short lived memory objects. Do that in a hot code path and suddenly you've got tremendous garbage pressure your garbage collector is going to choke on.One can optimise this by calculating results into a cached array, but that creates opportunities for bugs (results of previous caches persisting). I would dearly love to see a solution that allows me to code in a functional style without sacrificing performance.