Re: Continuations

["andrew cooke" <address@hidden>]

Dan Sugalski said:
>[in reply to:]
>>Don't Perl or Java programmers ever write interpreters?
>
> Rarely. These days almost *nobody* writes interpreters. But, then
> almost nobody ever has. In the past there were just fewer people
> overall, so almost nobody was a larger percentage of the population.
> I suspect you're also hanging around a rather unusual subset of
> programmers, which is a common thing for the people on this list.

I'm not sure how true this is - I think it may also be that many people
forget, or never learn, or simply don't realise, and so end up writing 
interpreteres without really noticing.

My previous (as of Friday - hurray!) job was J2EE (Java server side)
programming, with no previous experience, in an environment where
requirements changed daily and no design (or any other documentation)
existed - the kind of horror story that is probably all too typical(*). 
The end result was something - you'll have to take my word for it, as I'm
not going to describe all the details - that is disturbingly like an
interpreter.  I only wish I had noticed earlier because, once the
comparison is made, the points where it fails are points where the code is
weakest.

Perhaps part of the difficulty in recognising the pervasive nature of
interpreters is that the lexing is often automated (in my case either a
SAX interface triggered by XML tokens, or components of a custom tag
library being called by the JSP engine).  I guess that's because lexing is
usually the easy bit...

Andrew

(*) And my next job, starting Tuesday, uses Fortran 66 (hidden behind a
preprocessor which, joy of joys, adds C's dynamic memory handling, but
with *even weaker* typing).  Maybe I should just let people pay to hit me
:o)

-- 
http://www.acooke.org/andrew