xxxxxx@gmail.com (Taylan Ulrich "Bayırlı/Kammer") writes:

> Add1 and sub1 are similarly trivial definitions, but if you say they're
> so common, then I have no problem adding them under misc. procedures.
> Will do in a moment.

I now defined:

=====
- `(hashtable-inc! hashtable key)` (procedure)
- `(hashtable-inc! hashtable key x)`

Effectively equivalent to:

    (hashtable-update! hashtable key (lambda (x) (+ x k)) 0)

where x is 1 when not provided.

- `(hashtable-dec! hashtable key)` (procedure)
- `(hashtable-dec! hashtable key x)`

Effectively equivalent to:

    (hashtable-update! hashtable key (lambda (x) (- x k)) #f)

where x is 1 when not provided.
=====

Are these OK?  In particular, is it OK that dec! errors when no
association exists, and inc! makes it start from 0 automatically?

Taylan