Informally, an effect handler is a way for a coroutine to answer to operations. An operation is identified with a label, and can have arguments. Every operation is dispatched to the nearest enclosing coroutine that has a handler for that operation.
A handler receives a continuation, and the arguments
for its operation. The continuation can be used to
resume the coroutine that sent the operation; any
arguments passed to it are returned from the call
to handler.op. Or the handler can ignore the
coroutine, stash it somewhere to be used later, etc.
If a coroutine finishes its return
values are dispatched to a return handler, if
present.
Install it by running luarocks make on the provided
rockspec file. The contrib folder has some libraries
that implement some abstractions on top of effect handlers,
and the samples folder has a sample script that shows
how different handlers compose seamlessly. Some of them depend on
the thread
library and on a branch of
Cosmo.
These two libraries depend on taggedcoro.