On 9/18/17 10:08 PM, Alan Mackenzie wrote:

> Thanks for this.  I'm impressed.  Your syntax-ppss--data is far more
> elegant than my syntax-ppss-set-cache.  The burden of carrying around
> the caches in cons cells is much less than I had feared.  The amendments
> to syntax-ppss are also less than I had feared, amounting to little more
> than substituting "syntax-ppss-cache" with "ppss-cache" etc., and making
> a few bindings to support that.

Thanks!

> I notice you flush both caches eagerly, as you said you would.  No harm
> in that.
> 
> So, I'm willing to go with your version.  I haven't tried actually
> running it, yet.

Please do.

> But there's one small change I would ask you to consider making - that
> is, in the cache conses, to put ppss-last in the car and ppss-cache in
> the cdr.  That way, while debugging, ppss-last will be easy to find
> (it's the first element of the list) and ppss-cache will also be easy to
> find (the second element onwards).

Sure, that makes a lot of sense, since ppss-last is a smaller structure. 
The modified patch is attached.