Hi Tomas,
sorry for the late reply, but I wanted first to get picoLisp-3.0 out of
the door.
> >> defined: The dot is allowed as _part_ of a symbol name, but _not_ as
> >> a symbol name per se. A stand-alone dot is a meta character.
> ...
> I don't think so. I have simple rules for the reader:
> - dot is a symbol as any other
> - if read inside a list, it means: place the next sexp into the current
> cells' cdr
> - if the dot is the last sexp in the list, make the list circular
I see your point. When the dot is no longer a meta character, the
ambiguity cause by the "dual nature" is resolved.
However, you get into another dilemma: Despite the fact that the dot is
a legal internal symbol, you can never read it in a list, not even by
escaping it. It is a kind of meta-symbol, solely for the reader.
> I don't think it can get any simpler. And it is definitely much simpler
> and more logical than the PicoLisp reader and any other Lisp reader I've
> seen so far.
Hmm, not sure. The current reader is (when you ignore special cases like
NIL, read-macros, superparens etc.) in pseudo code:
(de read ()
(ifn (= "(" NextToken)
(readAtom)
(make
(loop
(T (= ")" NextToken)
(skip) )
(T (= " . " NextToken)
(chain (read)) )
(link (read)) ) ) ) )
So the rule is that the dot is only treated as a meta-character when
- appearing in a list
- unescaped
- and not as part of a symbol
Cheers,
- Alex
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