Javascript preamble not working properly

[erlanger]

Not working in the playground

TypeError: replacement.expr is undefined chrworker.js:20:5

Must be a problem with the parser, maybe.

Failing also in node, in a different way

Using JS preamble:

{
  // preamble
  // code in this block can be used in the rules' guards and bodies

  function print (v) {
    console.log(v)
  }

  function pred (v) {
    return v < 5
  }
}

print_num     @ num(v) ==> ${ (v) => print(v) }
generate_nums @ num(v) ==> ${ (v) => pred(v) } | num(v+1)
//generate_nums @ num(v) ==> v < 5 | num(v+1)

produces this output:

1
ID  Constraint
--  ----------
1   num(1)

Should produce a sequence of numbers.

Works when using chr guards without calling javascript:

{
  // preamble
  // code in this block can be used in the rules' guards and bodies

  function print (v) {
    console.log(v)
  }

  function pred (v) {
    return v < 5
  }
}

print_num     @ num(v) ==> ${ (v) => print(v) }
//generate_nums @ num(v) ==> ${ (v) => pred(v) } | num(v+1) <--- commented out
generate_nums @ num(v) ==> v < 5 | num(v+1)

Produces the correct output:

1
2
3
4
5
ID  Constraint
--  ----------
1   num(1)
2   num(2)
3   num(3)
4   num(4)
5   num(5)

For reference the javascript calling code:

var chr = require('./t.js')
function pr() {
 console.log(chr.Store.toString()) 
}
chr.num(1).then(pr)