Does julia have a construct analogous to Racket's parameters?

General Usage
5

This is an interesting idea and probably Casette.jl or IRTools.jl is the best way to solve it.

On the other hand, to some extent it can be solved with usual macros (sorry, I am just thinking aloud, not sure if its doable in reality).

Idea is that your code roughly equivalent to

struct Foo
  world  # pointer to something interesting and contextual
  value  # just a Float64 perhaps
end


let world = "hello"
    mkFoo(x) = Foo(world, x)
    println(mkFoo(1))
end

i.e. if we create closure inside let block, than we are good to go. Of course, your example use function declaration outside of let block, in which case you can’t declare closure.

What can be done, is “storing” closure declaration somewhere and applying it afterwards, so for the end user, it looks like

@with_context world mkFoo(x) = Foo(world, x)

@in_context world = World(...) begin
  x = mkFoo(3)
  y = mkFoo(5)
...
end

And macro @in_context should generate these lines

let world = World(...) begin
  mkFoo(x) = mkFoo(world, x) # substitute from @with_context declaration

Of course, it’s very quickly became rather complicated: what should we do if we have more than one context? How can we decide which functions to use? And what can we do with nested @in_context?

So it looks like that building full scaled implementation in this approach is too complicated, but limited versions could exist.