Referring to field defined at outer most level at some inner level where duplicated field is present

[suimong]

Consider the following

# sample.ncl
{
  foo = 1,
  bar = {
    foo = 5,
  },
  baz = {
    foo = 3,
    cux = foo + 1,
  },

}

Now baz.cux evaluates to 4 which is expected, and as long as some foo is nested within another field, there's no problem referring to it (e.g. cux = bar.foo +1 evaluates to 6), but what if I want to refer to the outermost foo at baz.cux? I couldn't seem to find a way.

[yannham]

The simplest work around currently is to capture the external variable in a let binding before it's shadowed:

# sample.ncl
{
  foo = 1,
  bar = {
    foo = 5,
  },
  baz = let bar_foo = bar.foo in {
    foo = 3,
    cux = foo + bar_foo + 1,
  },
}

It can sometimes become a bit verbose. Possible future solutions could include special keywords like self/super. Alternatively, a nonrec keyword to specify that we want some records to not be recursive could also be a solution.

[suimong]

Another trick learned, thank you! Though for reference to future me or others stumbled upon this, what @yannham mean is:

# sample.ncl
{
  foo = 1,
  bar = {
    foo = 5,
  },
  baz = let outer_foo = foo in {  
    foo = 3,
    cux = foo + outer_foo + 1,  # evaluates to 5
  },
}

As for future solutions, I like the idea of self/super, but obviously it requires some thinking about its proper semantic and syntactic meaning, as well as the cost of introducing another keyword.