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Linear types support is coming along nicely, there is a fork of GHC with a prototype implementation. https://github.com/tweag/ghc/tree/linear-types https://git
by wz1000 9y ago
Linear types support is coming along nicely, there is a fork of GHC with a prototype implementation.
https://github.com/tweag/ghc/tree/linear-types https://github.com/tweag/ghc/tree/linear-types
However, to allow the compiler to optimise pure operations to impure ones, I don't think linear types are sufficient. You need something like uniqueness types.
- btcindivist 9y agoI think C++ compiles down to a pure functional language that is then optimized into an efficient beast. So I'm not sure that pure code is hard to optimize.
- seanmcdirmid 9y agoSSA is quite different from a pure FP; for example it doesn’t do anything about effects, it only gets rid of local imperative assignments that don’t really interfere with purity anyways.
- tathougies 9y agoMost imperative languages have an intermediate language in which local variables are immutable. However, purity is about more than immutability. For example, in C++ x = doSomething(x) + 1 Can be written to not overwrite x int x2 = doSomething(x) + 1 This is equivalent in some ways to Haskell let x' = doSomething x + 1 However, I know that in Haskell, evaluating 'doSomething x' will not turn off the computer, display anything to the user, or launch missiles. I have no idea what evaluating 'doSomething(x)' does in C++. It may add things to caches, exit the program, etc.