module javascript
imports libstrategolib signatures/- util

signature
  constructors
    TopLevel: Ex -> Ex

rules
  js: TopLevel(x) -> $[const Stdio = {
    receives: v => { process.stdout.write(String(v)); return Stdio; },
    forwards: v => { process.stdout.write(String(v)); return v; }
  }
  [x]]

  js: Stdio() -> $[Stdio]
  js: Int(x) -> x
  js: Sum(x) -> $[[x].reduce((v,w) => v+w)]
  js: Receives(x, y) -> $[[x].receives([y])]
  js: Enters(x, y) -> $[[y].forwards([x])]

  jslist: x -> $<[<<join(|", ")>x>]>

strategies
  // wrap expression in a toplevel, then generate code from bottom up
  javascript = !TopLevel(<id>); bottomup(try(js <+ jslist))

  // Interface javascript code generation with editor services and file system
  to-javascript: (selected, _, _, path, project-path) -> (filename, result)
    with filename := <guarantee-extension(|"js")> path
       ; result   := <javascript> selected