bootstrapping from ECHO (SPOILERS)

[Dave Long]

Just ran across someone doing a similar exercise:

http://code.google.com/p/scheme-from-scratch/

For what it's worth, I believe Lisp started life as an abstract  
pseudo-code that was hand-assembled, but once someone realized that  
eval was also within hackable grasp, an interpreter and subsequent  
compiler were not far off.

John McCarthy:
> Steve Russell said, look, why don't I program this eval..., and I  
> said to him, ho, ho, you're confusing theory with practice, this  
> eval is intended for reading, not for computing. But he went ahead  
> and did it. That is, he compiled the eval in my paper into [IBM]  
> 704 machine code, fixing bugs, and then advertised this as a Lisp  
> interpreter, which it certainly was. So at that point Lisp had  
> essentially the form that it has today....


In looking through my rudimentary python-based 8086 assembler, I'd  
guess a reasonable forward path might be:
0. hex/octal direct (tape-like) loader
1. (single character) labels, references (many possible  
implementations here!)
2. control structures (branches, loops)
3. full (or at least reasonable) length symbol table

It would even be possible to pipeline these steps, but then it might  
be useful to substitute (0a) a random-access loader (like SREC or  
HEX) to mitigate the two-pass nature of resolving references.

Many tradeoffs in early language implementation were due to the  
relatively small and slow machines; I wonder if we would depart from  
them now that the available "brute force" space has expanded  
significantly?

-Dave

see also:
http://www.gtoal.com/languages/bcpl/amiga/bcpl/booting.txt