[ajuc]

There's 2 different aspects people mean when they call sth functional programming:

- higher order functions (lambdas, currying, closures, etc.)

- pure functions, immutability by default, side effects are pushed to the top level and marked clearly

The first aspect of functional programming has been already accepted by most OOP languages (even C++ has lambdas and closures).

The second aspect of functional programming is what makes it useful on GPU (because GPU architecture that makes it so powerful requires no interactions between code fragments that are run in parallel on 1000s of cores). So you can easily run pure functional code on GPU, but you can't easily run imperative code on GPU.

You can introduce side effects to functional programming, but then it ceases to be any more useful for GPU (and other parallel programming) than imperative/OOP.