message: Support variable lookups
diff: @@ -60,9 +60,13 @@ function emitBril(prog: ts.Node): bril.Program {
  switch (expr.kind) {
  case ts.SyntaxKind.NumericLiteral:
  let lit = expr as ts.NumericLiteral;
  - let val = parseInt(lit.text);
  + let val = parseInt(lit.getText());
  return builder.buildConst(val);
  + case ts.SyntaxKind.Identifier:
  + let ident = expr as ts.Identifier;
  + return builder.buildOp(bril.OpCode.id, [ident.getText()]);
  +
  default:
  throw "unsupported expression kind";
  }
  