Packages - Lisp

Convention: Use uninterned symbols for package names and exports.

Rationale: We do this because, otherwise, we would have the following:

[1]> *package*
#<PACKAGE COMMON-LISP-USER>
[2]> (defpackage bar)
#<PACKAGE BAR>
[3]> (find-symbol "BAR")
BAR ;
:INTERNAL

But using uninterned symbols:

;; Uninterned symbols don't cause symbol pollution:
[4]> (defpackage #:foo)
#<PACKAGE FOO>
[5]> (find-symbol "FOO")
NIL ;
NIL

We could use strings, too, but in that case we would have to use SCREAMING CASE.

Convention: One package may have many files.

Rationale: Java required 1 class per file, and organized classes into packages and subpackages. Many languages copied this convention, and it seems to have become a ubiquitous convention.

Common Lisp doesn't quite follow this pattern. But it may be useful to have 1 file per class (so as to quickly find relevant code). In that case, we would have a package generically look like:

• class_1.lisp
• …
• class_N.lisp
• package.lisp lists the defpackage declarations

Examples of this:

• CFFI
• Quicklisp for multiple defpackage declarations