[memefrog]

It's not really Rust's compiler that 'optimises lazy sequences'. It's LLVM, which notices that the code emitted happens to be able to be optimised down, if you run it for a really, really long time with some very strong optimisations.

GHC would be a better example, I think. It performs stream fusion. This means it can turn 'map f (map g xs)' into 'map (f . g) xs', and of course it gets more complex than that, but that's the basics. It directly optimises lists (which, this being Haskell, are lazy sequences).

[vbezhenar]

> GHC would be a better example, I think. It performs stream fusion. This means it can turn 'map f (map g xs)' into 'map (f . g) xs', and of course it gets more complex than that, but that's the basics. It directly optimises lists (which, this being Haskell, are lazy sequences).

Is it for built-in map or it would work in a general way for, say, `myMap f (myMap g xs)` ?

[consilient]

> Is it for built-in map or it would work in a general way for, say, `myMap f (myMap g xs)` ?

Just the stdlib `map`, but it's all ordinary library code. You can easily add your own rewrite rules.