The second talk in [Miguel Sofer]'s NRE series at [Tcl2008], following up on [NRE: the non-recursive engine in Tcl 8.6]:

Coroutines--what?
   * A computation that can be suspended and resumed on demand or killed while suspended
   * A tool to create ''generators''
   * A tool to simplify the coding of event-based programs
   * A tool to enable cooperative multitasking within a single interp, without OS support

TIP #328 specifies three new commands: [coroutine], [yield], and [info coroutine].  [[coroutine]] is evaluated equivalently to ''uplevel #0 [[list cmd ?arg ...?]]''.  [[yield]] suspends operation.  Walked through an example from the tip.

[[yield]] returns twice: when yielding (caller reeives a return value from the yielding coroutine); when resuming coroutine sees the [[yield]] command returning.  [[''cmdName'']] is "garbage collected".  Example at http://msofer.com:8080/wiki?name=Coroutines

Went through the wiki page [Coroutines for event-based programming] showing converting a console application to a GUI.

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