`catch` operator?

[lhmouse]

catch EXPRESSION catch(EXPRESSION) is equivalent to

(func() {
  try {
    (EXPRESSION);
    return null;
  }
  catch(e)
    return e;
}())

which is primarily useful in unit testing.

[lhmouse]

There is technical limitation, though:

In order for catch to catch exceptions that are effected by invalid expressions, its operand must be evaluated in a separate context. For example, the expression

catch(1/0)

is parsed (in Reverse Polish Notation) as

1 0 / catch

where the division operator effects an exception before the catch operator is encountered. For the catch operator to work expectedly, new syntax construction has to be set up.

[lhmouse]

This is resolved by requiring a pair of parenthesis around the operand.