[ I guess opening a socket to the db server and parsing the resultset wouldn't be much harder if its text mode - could probably use the perl or ruby pglib as a guide, and port from that... ]
Hmm. I would think that you wouldn't want to open a new psql connection every time you want to look something up.
How about running the system command in a thread, which redirects psql's stdin and stdout to named pipes so that another arc thread could read from it using file read commands? That would give you more persistence, so you wouldn't have to keep loading psql.
Also, have a look at lib/mysql-ffi.arc in anarki; supposedly it has a ffi for mysql, though I haven't really looked at it much myself.
In fact I wonder if anyone has ported pg's Arc macros to Scheme... it seems a lot of the benefit of the language would still be there without a full Arc syntax implementation.
It could be seen as an experiment to see how much an Arc without special language extensions would feel like the real Arc - eg. minus square brackets etc.
My feeling is that merely having nice short abbreviations buys quite a lot - but hell, Ive written mostly C code, so you may rightly cringe at the lobotimization.