Anonymous user
Talk:S-expressions: Difference between revisions
→Existing Standards: Discussion of character syntax types in CL.
(→Existing Standards: Discussion of character syntax types in CL.) |
|||
Line 16:
Common Lisp: ANSI Standard available in the form of the [[http://www.lispworks.com/documentation/HyperSpec/Front/index.htm Common Lisp HyperSpec]]. The reader syntax is described in [[http://www.lispworks.com/documentation/HyperSpec/Body/02_.htm Syntax]].
:this page describing the [http://www.lispworks.com/documentation/HyperSpec/Body/02_ad.htm Character Syntax Types] seems most interestung.--[[User:EMBee|eMBee]] 02:07, 20 October 2011 (UTC)
::Yes. In Common Lisp, the reading is very simple. Characters are assigned to categories in a read-table (in a context-independent way). The reader takes a character and based on what category it is in, it assembles it into a token, or dispatches a function associated with that character. Donald Knuth's TeX has a similar approach: it also has character categories (which TeX code can manipulate).[[Special:Contributions/24.85.131.247|24.85.131.247]] 02:22, 20 October 2011 (UTC)
::Note that there is a category of "non-terminating" macro characters. This means that if they are part of a token, they behave like token constituents. The # macro dispatch character is this way, so for instance abc#def is actually a symbol with the name "ABC#DEF": the special meaning of # is defeated. If it were a terminating character, then its presence would signal the end of the token ABC. The parentheses are terminating, needless to say: (abc) is not a single token, but the same as ( abc ). Lisp tries to allow the programmer to have a lot of freedom in what constitutes a symbol. Just because some symbol has a special meaning doesn't mean we have to inconvenience ourselves by making it difficult to have that character in the middle of a symbol. This is quite important if you're doing domain-specific things where the symbol syntax comes from some outside domain. Another example is the writing of compilers where you have to deal with symbols from another programming language, as well as low-level symbols used by assemblers and linkers. It's not hard to map these to "native" symbols.[[Special:Contributions/24.85.131.247|24.85.131.247]] 02:22, 20 October 2011 (UTC)
ISO Standard Lisp: Also known as [[http://islisp.info/ ISLisp]].
| |||