// first, let's see what functions and function calls look like

BSJSParser.matchAll("function(x) { foo(); return x + 1 }", "srcElem")


// now we know enough to extend our JS with a BCPL-inspired valof expression

oldBSJSParser = BSJSParser

ometa newBSJSParser <: oldBSJSParser {
  isKeyword :x = ?(x == 'valof')
               | super(`isKeyword, x),
  expr         = "valof" "{" valofBody:r "}"     -> r
               | super(`expr),
  valofBody    = notLast(`srcElem)*:ss expr:r sc -> { ss.push([`return, r])
                                                      [`call, [`func, [], [`begin].concat(ss)]] }
}
newBSJSParser.matchAll("f = function(x) { return valof { x++; x * x } }", "srcElem")