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                         PLN CDR DRAFT: ISSUE 1

                                Gleefre
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1 Issue 1 (ADD-/REMOVE-PACKAGE-LOCAL-NICKNAME return values)
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1.1 Description
───────────────

  Functions `add-package-local-nickname' and
  `remove-package-local-nickname' have inconsistent return values.

  The first one always returns the /designated package/, while the
  second one returns /true/ (a /generalized boolean/) that indicates
  whether a nickname was removed.

  Furthermore, there is no consensus among existing implementations as
  to what this /generalized boolean/ represents.

  In comparison,the functions `use-package' and `unuse-package' always
  return `T', and the functions `export' and `unexport' have the same
  behavior. There are also functions `unintern' and `delete-package'
  which return a /generalized boolean/ indicating if the operation
  changed something, but their counterparts `intern' and `make-package',
  unlike with local nicknames, create and return an /object/ (a /symbol/
  or a /package/).


1.2 Examples
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  ┌────
  │ (defpackage #:foo (:use))
  │ (defpackage #:bar (:use))
  │ 
  │ (add-package-local-nickname '#:nick '#:bar '#:foo)
  │ ; => #<PACKAGE "FOO">  (sbcl, ccl, ecl, acl, abcl, clasp, lispworks)
  │ (add-package-local-nickname '#:nick '#:bar '#:foo)
  │ ; => #<PACKAGE "FOO">  (sbcl, ccl, ecl, acl, abcl, clasp, lispworks)
  │ (remove-package-local-nickname '#:nick '#:foo)
  │ ; => T  (sbcl, ccl, ecl, acl, clasp)
  │ ; => #<PACKAGE "BAR">  (abcl)
  │ ; => NIL  (lispworks)
  │ (remove-package-local-nickname '#:nick '#:foo)
  │ ; => NIL  (sbcl, ccl, ecl, acl, abcl, clasp, lispworks)
  └────


1.3 Current behavior
────────────────────

  sbcl, ccl, ecl, acl, abcl, clasp, lispworks:
    `add-package-local-nickname' always returns /designated package/.

  sbcl, ccl, ecl, acl, clasp: `remove-package-local-nickname' returns
    `T' if a nickname was removed, and `NIL' otherwise.

  abcl: `remove-package-local-nickname' returns /true/ if a nickname was
    removed, (more specifically, it returns the package nicknamed by the
    removed local nickname), and `NIL' otherwise.

  lispworks: `remove-package-local-nickname' always returns `NIL'.


1.4 Proposal ALWAYS-T
─────────────────────

  `add-package-local-nickname' should always return `T'.

  `remove-package-local-nickname' should always return `T'.


1.5 Proposal ELIMINATE-GENERALIZED-BOOLEAN
──────────────────────────────────────────

  `add-package-local-nickname' should return the /designated package/.

  `remove-package-local-nickname' should return `T' if a nickname was
  removed and `NIL' otherwise.


1.6 Proposal DESIGNATED-PACKAGE-IF-SUCCESSFUL
─────────────────────────────────────────────

  `add-package-local-nickname' should return the /designated package/ if
  a new nickname was added, and `NIL' otherwise.

  `remove-package-local-nickname' should return the /designated package/
  if a nickname was removed, and `NIL' otherwise.


1.7 Proposal NICKNAMED-PACKAGE-IF-SUCCESSFUL
────────────────────────────────────────────

  `add-package-local-nickname' should return the /nicknamed package/ if
  a new nickname was added, and `NIL' otherwise.

  `remove-package-local-nickname' should return the previously
  /nicknamed package/ if a nickname was removed, and `NIL' otherwise.