How would shallow generators compose with lambda?

Waldemar Horwat waldemar at
Thu May 14 18:04:07 PDT 2009

Brendan Eich wrote:
> On May 14, 2009, at 1:47 PM, Waldemar Horwat wrote:
>> This whole thing is another nail in the coffin of generators.  
>> Generators are the root of the troublesome longjmp's which don't play 
>> well with others.
> Are you talking about generators, or lambdas?

Generators.  They cause control flow to jump around between two independent functions.

THe same problem occurs without lambdas:

function gen(arg) {
  try {
    yield 1;
    yield 2;
  } finally {
    alert("Finally called up to three times?!");

That finally will be called either 1, 2, or 3 times depending on what the caller does, which violates the principle that finally is called exactly once, no matter how you leave a scope.


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