[cryptonector]

> The symmetry implies the support for multiple return values.

Yes!

> Multiple values are tricky. 100% symmetry is never achieved with those things. The problem is that [...]

You basically need destructuring on the return values, and the syntax for that has to be fairly clean. And for the example you give where one function's return value(s) is(are) passed to another's things do get tricky: shall that use only the first value returned? or maybe the whole lot of them (as an array/list)? or both, where if the callee doesn't treat the thing as an array/list then it's the first value (implying dynamic typing)? or does what happens depend on the callee's parameter's type? or what? Yeah, it's very tricky.

Another option is to have generators, and if a function returns/yields multiple values in one go, maybe treat them as single values yielded separately. This one isn't that awesome either.

> We can also go the other way: declare that functions should not only return exactly one value, but only take exactly one argument. That is also symmetric! Then currying can be used to combine functions in order to simulate multiple arguments.

Yes :)

But then in Haskell, which does this, we end up with syntactic sugar with which to pretend there's multiple arguments, thus the 100% symmetry isn't quite.

Oh well.