a REPL with structured output (for programs)
reads forms to eval from in-reader (a LineNumberingPushbackReader)
Closing the input or passing the form :repl/quit will cause it to return
Calls out-fn with data, one of:
{:tag :ret
:val val ;;eval result, or Throwable->map data if exception thrown
:ns ns-name-string
:ms long ;;eval time in milliseconds
:form string ;;iff successfully read
:exception true ;;iff exception thrown
}
{:tag :out
:val string} ;chars from during-eval *out*
{:tag :err
:val string} ;chars from during-eval *err*
{:tag :tap
:val val} ;values from tap>
You might get more than one :out or :err per eval, but exactly one :ret
tap output can happen at any time (i.e. between evals)
If during eval an attempt is made to read *in* it will read from in-reader unless :stdin is supplied
Alpha, subject to change.