Undefined function: prior

[FrankChung]

I have a bolt file as follow:

path /test is Map<Test, String> {}

type Test extends String {
  validate() { prior(root) != null }
}

I got an error as:
bolt: Generating test.json...
bolt:1:1: Undefined function: prior
bolt: Could not generate JSON: 1 errors.

But if I don't put the Test type as a key of the map, it compiles correctly.

[mckoss]

Thanks for the minimal reproducible test case! I fixed this in PR #170.