The next step from this is in languages like Haskell, where function currying is the same as function calling, and everything is lazy. There's effectively no di

The next step from this is in languages like Haskell, where function currying is the same as function calling, and everything is lazy. There's effectively no difference between a function with all the arguments filled out, and the value it returns – at least most of the time you don't need to care about the difference. Partial function application is incredibly ergonomic in the language too.