Re: CPS in Parrot (was: A plea for a new old language)

[Dan Sugalski <address@hidden>]

At 3:22 PM -0400 8/5/03, Geoffrey Knauth wrote:
>On Tuesday, Aug 5, 2003, at 13:00 US/Eastern, Dan Sugalski wrote:
>>I'm convinced at this point that all of the fear people have about 
>>continuations is a direct result of how they're taught and what's 
>>associated with them
>
>I haven't feared what I don't know.  I'm afraid to ask, "What's 
>associated with them?"

Lisp and/or Scheme, though the way the design of computer languages 
is taught (or, rather, not taught, until far too late) doesn't help. 
The only place continuations are brought up, assuming they're dealt 
with at all, is in a Lisp class, but not until the students have 
already had a number of years (upwards of 5-10 for some) of 
procedural and/or OO programming (C, C++, VB, even Java to some 
extent), which hammers some assumptions about the intrinsic 
stack-based nature of control-flow into students heads.

So, they walk into a lisp class with either the C model or the BASIC 
"They're all globals!" model deeply internalized, then get hit in 
rapid succession by Lisp's very different paradigm then a control 
flow and variable model completely at odds with what they know to be 
true. You then end up with a class full of people that either dislike 
continuations because they clash with what they know to be true about 
control and/or variables, or dislike continuations because lisp 
clashes with what they know and any concepts introduced with it get 
disliked by association. (Or they never understood it in the first 
place because they couldn't get past the confusion of dealing with a 
functional language, so everything explained in terms of the language 
didn't stick)

It doesn't help that many of the folks publicly advocating 
continuations tend to be a little... odd, so when you do run across a 
paper or proposal, your first impression is that the author's either 
mad or doing the CS equivalent of particle physics.

Not true for everyone, certainly -- a lot of people never get taught 
anything about continuations, and all they know about them is that 
most folks think they're Deep Black Magic.
-- 
                                         Dan

--------------------------------------"it's like this"-------------------
Dan Sugalski                          even samurai
dan@sidhe.org                         have teddy bears and even
                                       teddy bears get drunk