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Issue IN-SYNTAX Writeup

Status: Passed, Mar 89 X3J13


Edit History: 21-Oct-88, Version 1 by Pitman

Version 2, KMP 3/30/89

Version 3, 9-Apr-89, Masinter

(Include discussion from Version 1)

Problem Description:

There is no way to bind read syntax within a file.

As a result, applications which require extended syntax of some sort

tend to globally modify the lisp readtable at compile and load time,

sometimes interfering with other modules and/or user interaction.

Conscientious developers often avoid the creation of any stylized

syntax because of its likely effect on parts of the environment which

don't really belong to the application developer. This need for

paranoia is probably contrived and the result of what amounts to

an oversight in the design of Common Lisp.


Define that COMPILE-FILE and LOAD bind *READTABLE* to its current value.


This allows portable programs to do




at the top of a file without globally side-effecting the


Currently, there is no portable way to change the syntax only for

the duration of a file, which in turn makes customized syntax

difficult to use safely.

Programs that want to side effect the environment can instead

continue to modify *READTABLE*.

This is enough of a foothold to implement a more elaborate facility

for using readtables in a localized way.

Current Practice:


Cost to Implementors:

Very small.

Cost to Users:


Cost of Non-Adoption:

Readtables would continue to be hard to use in a clean way.


If people could use readtables safely, we might see more interesting

experimentation with read syntax.


A slight improvement to aesthetics by controlling what was formerly

an unbounded side-effect (modification to the global readtable).

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