Add quasiquoting and reader prefix macros
This adds a new QQ
package to the standard library, which when USE
d, changes the backtick character ` to a "quasiquote" as seen in more modern Lisp derivatives.
`<FOO ~.BAR>
is equivalent to
<FORM FOO .BAR>
and
`<FOO ~!.BAR>
is equivalent to
<FORM FOO !.BAR>
The ` and ~ prefixes are implemented with another new package, READER-MACROS
, which is built into ZILF. We still don't have a full implementation of read tables, but READER-MACROS
could be changed to use read tables if they're added someday.