unsafePerformEffect

[jamesdbrock]

Is it a good idea to run execPut in unsafePerformEffect? I suspect that it is a very good idea.

[jamesdbrock]

Dear computer programmer, you should definitely call execPut inside unsafePerformEffect (if you want to).

The reason why this whole library is Effectful is that ArrayBuffers are mutable, so by default, the ArrayBuffer library functions do everything in Effect to enlist the compiler to confirm that any mutations are properly sequenced.

However, all of the put functions in this library are actually side-effect free, so we can use unsafePerformEffect to tell the compiler to trust that we don't perform any side-effects while we're building an ArrayBuffer.

let pureArrayBuffer :: ArrayBuffer
    pureArrayBuffer = serializer 2

serializer :: Int -> ArrayBuffer
serializer x = unsafePerformEffect $ execPut $ do
  putInt32be x                                -- ✅ Good, this has no side-effects
  putInt32be =<< getCurrentPosixTime          -- ❌ NO NO DON'T DO THIS INSIDE unsafePerformEffect
  putArrayBuffer =<< readFileFromMyFilesystem -- ❌ NO WE ARE GONNA GET SO BURNED

Caveat emptor.