# Named Readtables Manual
###### \[in package EDITOR-HINTS.NAMED-READTABLES\]
## named-readtables ASDF System Details
- Version: 0.9
- Description: Library that creates a namespace for named readtable
akin to the namespace of packages.
- Licence: BSD, see LICENSE
- Author: Tobias C. Rittweiler <email@example.com>
- Maintainer: G?bor Melis
- Mailto: [firstname.lastname@example.org](mailto:email@example.com)
Named-Readtables is a library that provides a namespace for
readtables akin to the already-existing namespace of packages. In
- you can associate readtables with names, and retrieve
readtables by names;
- you can associate source files with readtable names, and be
sure that the right readtable is active when compiling/loading
- similiarly, your development environment now has a chance to
automatically determine what readtable should be active while
processing source forms on interactive commands. (E.g. think of
`C-c C-c` in Slime (yet to be done))
It follows that Named-Readtables is a facility for using readtables in
a localized way.
Additionally, it also attempts to become a facility for using
readtables in a *modular* way. In particular:
- it provides a macro to specify the content of a readtable at a
- it makes it possible to use multiple inheritance between readtables.
Here is the [official repository][named-readtables-repo] and the
[HTML documentation][named-readtables-doc] for the latest version.
Thanks to Robert Goldman for making me want to write this library.
Thanks to Stephen Compall, Ariel Badichi, David Lichteblau, Bart
Botta, David Crawford, and Pascal Costanza for being early adopters,
providing comments and bugfixes.
### Notes on the API
The API heavily imitates the API of packages. This has the nice
property that any experienced Common Lisper will take it up without
DEFREADTABLE - DEFPACKAGE
IN-READTABLE - IN-PACKAGE
MERGE-READTABLES-INTO - USE-PACKAGE
MAKE-READTABLE - MAKE-PACKAGE
UNREGISTER-READTABLE - DELETE-PACKAGE
RENAME-READTABLE - RENAME-PACKAGE
FIND-READTABLE - FIND-PACKAGE
READTABLE-NAME - PACKAGE-NAME
LIST-ALL-NAMED-READTABLES - LIST-ALL-PACKAGES
### Important API idiosyncrasies
There are three major differences between the API of Named-Readtables,
and the API of packages.
1. Readtable names are symbols not strings.
Time has shown that the fact that packages are named by strings
causes severe headache because of the potential of package names
colliding with each other.
Hence, readtables are named by symbols lest to make the
situation worse than it already is. Consequently, readtables
named `CL-ORACLE:SQL-SYNTAX` and `CL-MYSQL:SQL-SYNTAX` can
happily coexist next to each other. Or, taken to an extreme,
`SCHEME:SYNTAX` and `ELISP:SYNTAX`.
If, for example to duly signify the importance of your cool
readtable hack, you really think it deserves a global name, you
can always resort to keywords.
2. The inheritance is resolved statically, not dynamically.
A package that uses another package will have access to all the
other package's exported symbols, even to those that will be
added after its definition. I.e. the inheritance is resolved at
run-time, that is dynamically.
Unfortunately, we cannot do the same for readtables in a
Therefore, we do not talk about "using" another readtable but
about "merging" the other readtable's definition into the
readtable we are going to define. I.e. the inheritance is
resolved once at definition time, that is statically.
(Such merging can more or less be implemented portably albeit at
a certain cost. Most of the time, this cost manifests itself at
the time a readtable is defined, i.e. once at compile-time, so
it may not bother you. Nonetheless, we provide extra support for
Sbcl, ClozureCL, and AllegroCL at the moment. Patches for your
implementation of choice are welcome, of course.)
3. DEFREADTABLE does not have compile-time effects.
If you define a package via DEFPACKAGE, you can make that
package the currently active package for the subsequent
compilation of the same file via IN-PACKAGE. The same is,
however, not true for DEFREADTABLE and IN-READTABLE for the
It's unlikely that the need for special reader-macros arises for
a problem which can be solved in just one file. Most often,
you're going to define the reader macro functions, and set up
the corresponding readtable in an extra file.
If DEFREADTABLE had compile-time effects, you'd have to wrap
each definition of a reader-macro function in an EVAL-WHEN to
make its definition available at compile-time. Because that's
simply not the common case, DEFREADTABLE does not have a
If you want to use a readtable within the same file as its
definition, wrap the DEFREADTABLE and the reader-macro function
definitions in an explicit EVAL-WHEN.
### Preregistered Readtables
- NIL, :STANDARD, and :COMMON-LISP designate the
- :MODERN designates a *case-preserving* *standard-readtable*.
- :CURRENT designates the *current readtable*.
(:macro-char #\? #'elisp::read-character-literal t)
(:macro-char #\[ #'elisp::read-vector-literal t)
(:macro-char #\[ #'(lambda (stream char)
(read-delimited-list #\] stream)))
(:macro-char #\# :dispatch)
(:dispatch-macro-char #\# #\t #'scheme::read-#t)
(:dispatch-macro-char #\# #\f #'scheme::read-#f)
- [macro] DEFREADTABLE NAME &BODY OPTIONS
Define a new named readtable, whose name is given by the symbol NAME.
Or, if a readtable is already registered under that name, redefine
The readtable can be populated using the following OPTIONS:
- `(:MERGE READTABLE-DESIGNATORS+)`
Merge the readtables designated into the new readtable being
defined as per MERGE-READTABLES-INTO.
If no :MERGE clause is given, an empty readtable is used. See
- `(:FUSE READTABLE-DESIGNATORS+)`
Like :MERGE except:
Error conditions of type READER-MACRO-CONFLICT that are signaled
during the merge operation will be silently *continued*. It
follows that reader macros in earlier entries will be
overwritten by later ones. For backward compatibility, :FUZE is
accepted as an alias of :FUSE.
- `(:DISPATCH-MACRO-CHAR MACRO-CHAR SUB-CHAR FUNCTION)`
Define a new sub character `SUB-CHAR` for the dispatching macro
character `MACRO-CHAR`, per SET-DISPATCH-MACRO-CHARACTER. You
probably have to define `MACRO-CHAR` as a dispatching macro
character by the following option first.
- `(:MACRO-CHAR MACRO-CHAR FUNCTION [NON-TERMINATING-P])`
Define a new macro character in the readtable, per
SET-MACRO-CHARACTER. If `FUNCTION` is the keyword :DISPATCH,
`MACRO-CHAR` is made a dispatching macro character, per
- `(:SYNTAX-FROM FROM-READTABLE-DESIGNATOR FROM-CHAR TO-CHAR)`
Set the character syntax of TO-CHAR in the readtable being
defined to the same syntax as FROM-CHAR as per
- `(:CASE CASE-MODE)`
Defines the *case sensitivity mode* of the resulting readtable.
Any number of option clauses may appear. The options are grouped by
their type, but in each group the order the options appeared
textually is preserved. The following groups exist and are executed
in the following order: :MERGE and :FUSE (one
group), :CASE, :MACRO-CHAR and :DISPATCH-MACRO-CHAR (one group),
The readtable is defined at load-time. If you want to have it
available at compilation time -- say to use its reader-macros in the
same file as its definition -- you have to wrap the DEFREADTABLE
form in an explicit EVAL-WHEN.
On redefinition, the target readtable is made empty first before
it's refilled according to the clauses.
NIL, :STANDARD, :COMMON-LISP, :MODERN, and :CURRENT are
preregistered readtable names.
- [macro] IN-READTABLE NAME
Set *READTABLE* to the readtable referred to by the symbol NAME.
- [function] MAKE-READTABLE &OPTIONAL (NAME NIL NAME-SUPPLIED-P) &KEY MERGE
Creates and returns a new readtable under the specified
MERGE takes a list of NAMED-READTABLE-DESIGNATORS and specifies the
readtables the new readtable is created from. (See the :MERGE clause
of DEFREADTABLE for details.)
If MERGE is NIL, an empty readtable is used instead.
If NAME is not given, an anonymous empty readtable is returned.
An empty readtable is a readtable where each character's syntax is
the same as in the *standard readtable* except that each macro
character has been made a constituent. Basically: whitespace stays
whitespace, everything else is constituent.
- [function] MERGE-READTABLES-INTO RESULT-READTABLE &REST NAMED-READTABLES
Copy the contents of each readtable in NAMED-READTABLES into
If a macro character appears in more than one of the readtables,
i.e. if a conflict is discovered during the merge, an error of type
READER-MACRO-CONFLICT is signaled.
- [function] FIND-READTABLE NAME
Looks for the readtable specified by NAME and returns it if it is
found. Returns NIL otherwise.
- [function] ENSURE-READTABLE NAME &OPTIONAL (DEFAULT NIL DEFAULT-P)
Looks up the readtable specified by NAME and returns it if it's found.
If it is not found, it registers the readtable designated by DEFAULT
under the name represented by NAME; or if no default argument is
given, it signals an error of type READTABLE-DOES-NOT-EXIST
- [function] RENAME-READTABLE OLD-NAME NEW-NAME
Replaces the associated name of the readtable designated by
OLD-NAME with NEW-NAME. If a readtable is already registered under
NEW-NAME, an error of type READTABLE-DOES-ALREADY-EXIST is
- [function] READTABLE-NAME NAMED-READTABLE
Returns the name of the readtable designated by NAMED-READTABLE,
- [function] REGISTER-READTABLE NAME READTABLE
Associate READTABLE with NAME. Returns the readtable.
- [function] UNREGISTER-READTABLE NAMED-READTABLE
Remove the association of NAMED-READTABLE. Returns T if successfull,
- [function] COPY-NAMED-READTABLE NAMED-READTABLE
Like COPY-READTABLE but takes a NAMED-READTABLE-DESIGNATOR as argument.
- [function] LIST-ALL-NAMED-READTABLES
Returns a list of all registered readtables. The returned list is
guaranteed to be fresh, but may contain duplicates.
- [type] NAMED-READTABLE-DESIGNATOR
Either a symbol or a readtable itself.
- [condition] READER-MACRO-CONFLICT READTABLE-ERROR
This condition is signaled during the merge process if a reader
macro (be it a macro character or the sub character of a dispatch
macro character) is present in the both source and the target
readtable and the two respective reader macro functions differ.
- [condition] READTABLE-DOES-ALREADY-EXIST READTABLE-ERROR
- [condition] READTABLE-DOES-NOT-EXIST READTABLE-ERROR
* * *
###### \[generated by [MGL-PAX](https://github.com/melisgl/mgl-pax)\]