[reactive] 'stateE' --> 'mealy'

Robin Green greenrd at greenrd.org
Tue Nov 25 14:11:31 EST 2008

On Mon, 24 Nov 2008 20:27:34 -0800
"Conal Elliott" <conal at conal.net> wrote:

> I renamed 'stateE' and 'stateE_' to' mealy' and 'mealy_' in
> reactive-0.9.4 (just released).  I've been meaning to change these
> names for a while now. I prefer these new names as being more clear &
> specific and connecting clearly to automata theory rather than to
> imperative programming.

I don't think mealy is as general as a Mealy machine, so this seems
misleading. A Mealy machine can jump to different states depending on
its input. If 's' is the state type, and 'b' the input type (which
seems to me to be the natural way to interpret it), that
"conditional jumping" feature isn't present.

I think

\f g a e -> f <$> scanlE g a e

is precisely a *Moore* machine, though? If so, scanlE is a particular
kind of Moore machine in which f is the identity. And so are the other
scanl* functions in the library - right?

More information about the Reactive mailing list