multiple value return error when using pipe operators

[cderici]

I was just playing with rash and noticed the following:

> ls |> (lambda (s) (values 1 2))
Result 46:
result arity mismatch;
 expected number of values not received
  expected: 1
  received: 2
  values...:
   1
   2

It fails similarly when using |>> as well.

[willghatch]

Thanks for trying Rash! Yes, currently pipelines expect a single return value. I've considered changing it to accept multiple values and automatically convert it to a list, but I'm hesitant to do that. You can use `call-with-values` to turn multiple values into a list instead, or there are a couple of modules that export a `values->list` macro that makes this more convenient (eg. br/list has one). Does that work for you?

[willghatch]

Or better stated, it is easy to make a custom pipeline operator macro that supports multiple values, but that wouldn't bring support to every operator. Are there compelling reasons you want to use multiple values in pipelines where converting them to a list in the function you use or using a multiple values operator doesn't work or is inconvenient?