Evaluating Medley compatibility with Practical Common Lisp code: Chapter 21

[pamoroso]

Chapter 21. Programming in the Large: Packages and Symbols

This is the continuation of the work on issue #609. To evaluate the compatibility of Medley Common Lisp with ANSI Common Lisp I'm testing on Medley the code of Peter Seibel's book Practical Common Lisp.

Issues

To prepare for chapter 21 I started adding the usual missing definitions and calls, particularly this package whose symbols are accessed later in the code:

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export :open-db   
           :save
           :store))

But evaluating it yields the error Not an existing package, string or symbol. So I rewrote it in two steps, first to define the package and then to define and export the symbols:

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp))

(defun com.gigamonkeys.text-db::open-db () t)

(defun com.gigamonkeys.text-db::save () t)

(defun com.gigamonkeys.text-db::store () t)

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export :open-db   
           :save
           :store))

This leads to the same error Not an existing package, string or symbol though.

Code

Here is the code of the initial part of the chapter:

(eql ':foo :foo)

(symbol-name :foo)

(eql '#:foo '#:foo)

(gensym)

*package*

; TEST
common-lisp:*package*

cl:*package*

(defvar *x* 10)

*x*

:a

keyword:a

(eql :a keyword:a)

(defpackage :com.gigamonkeys.email-db
  (:use :common-lisp))

(defpackage "COM.GIGAMONKEYS.EMAIL-DB"
  (:use "COMMON-LISP"))

(in-package :com.gigamonkeys.email-db)

(defun hello-world () (format t "hello from EMAIL-DB package~%"))

(hello-world)

(in-package :xcl-user)

(defun hello-world () (format t "hello from XCL-USER package~%"))

(hello-world)

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp))

(defun com.gigamonkeys.text-db::open-db () t)

(defun com.gigamonkeys.text-db::save () t)

(defun com.gigamonkeys.text-db::store () t)

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export :open-db   
           :save
           :store))

(defpackage :com.gigamonkeys.email-db
  (:use :common-lisp :com.gigamonkeys.text-db))

Session transcript

And this is the transcript of the test session with the errors:

2/8> (eql ':foo :foo)
T
2/9> 

2/9> (symbol-name :foo)
"FOO"
2/10> 

2/10> (eql '#:foo '#:foo)
NIL
2/11> 

2/11> (gensym)
#:G30
2/12> 

2/12> *package*
#<Package XCL-USER>
2/13> 
; TEST
common-lisp:*package*
#<Package XCL-USER>
2/14> 
cl:*package*
#<Package XCL-USER>
2/15> 
(defvar *x* 10)
*X*
2/16> 

2/16> *x*
10
2/17> 
:a
:A
2/18> 
keyword:a
:A
2/19> 
(eql :a keyword:a)
T
2/20> 

2/20> (defpackage :com.gigamonkeys.email-db
  (:use :common-lisp))
"COM.GIGAMONKEYS.EMAIL-DB"
2/21> 

2/21> (defpackage "COM.GIGAMONKEYS.EMAIL-DB"
  (:use "COMMON-LISP"))
"COM.GIGAMONKEYS.EMAIL-DB"
2/22> 

2/22> (in-package :com.gigamonkeys.email-db)
#<Package COM.GIGAMONKEYS.EMAIL-DB>
2/23> 

2/23> (defun hello-world () (format t "hello from EMAIL-DB package~%"))
HELLO-WORLD
2/24> 

2/24> (hello-world)
hello from EMAIL-DB package
NIL
2/25> 

2/25> (in-package :xcl-user)
#<Package XCL-USER>
2/26> 

2/26> (defun hello-world () (format t "hello from XCL-USER package~%"))
HELLO-WORLD
2/27> 

2/27> (hello-world)
hello from XCL-USER package
NIL
2/28> 

2/28> (defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export :open-db   
           :save
           :store))
Not an existing package, string or symbol 
NIL

2/29> 

2/29> (defpackage :com.gigamonkeys.text-db
  (:use :common-lisp))
"COM.GIGAMONKEYS.TEXT-DB"
2/30> 

2/30> (defun com.gigamonkeys.text-db::open-db () t)
COM.GIGAMONKEYS.TEXT-DB::OPEN-DB
2/31> 

2/31> (defun com.gigamonkeys.text-db::save () t)
COM.GIGAMONKEYS.TEXT-DB::SAVE
2/32> 

2/32> (defun com.gigamonkeys.text-db::store () t)
COM.GIGAMONKEYS.TEXT-DB::STORE
2/33> 

2/33> (defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export :open-db   
           :save
           :store))
Not an existing package, string or symbol 
NIL

2/34> 

[pamoroso]

The fix

I fixed the Not an existing package, string or symbol issue by rewriting the package definition in two steps as above. In addition I specified fully qualified symbols in the package redefinition of the second step, like this:

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export com.gigamonkeys.text-db::open-db   
           com.gigamonkeys.text-db::save
           com.gigamonkeys.text-db::store))

I also needed to substitute :import and :shadowing-import for :import-from and :shadowing-import-from in defpackage. :import-from and :shadowing-import-from are missing from Medley which, however, provides the alternate keywords.

Code

With these changes I was able to run the full code of chapter 21:

(eql ':foo :foo)

(symbol-name :foo)

(eql '#:foo '#:foo)

(gensym)

*package*

common-lisp:*package*

cl:*package*

(defvar *x* 10)

*x*

:a

keyword:a

(eql :a keyword:a)

(defpackage :com.gigamonkeys.email-db
  (:use :common-lisp))

(defpackage "COM.GIGAMONKEYS.EMAIL-DB"
  (:use "COMMON-LISP"))

(in-package :com.gigamonkeys.email-db)

(defun hello-world () (format t "hello from EMAIL-DB package~%"))

(hello-world)

(in-package :xcl-user)

(defun hello-world () (format t "hello from XCL-USER package~%"))

(hello-world)

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp))

(defun com.gigamonkeys.text-db::open-db () t)

(defun com.gigamonkeys.text-db::save () t)

(defun com.gigamonkeys.text-db::store () t)

(defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export com.gigamonkeys.text-db::open-db   
           com.gigamonkeys.text-db::save
           com.gigamonkeys.text-db::store))

(defpackage :com.gigamonkeys.email-db
  (:use :common-lisp :com.gigamonkeys.text-db))

(defpackage :com.acme.email
  (:use :common-lisp))

(defun com.acme.email::parse-email-address () t)

(defun com.acme.email::build-index () t)

(defpackage :com.acme.email
  (:use :common-lisp)
  (:export com.acme.email::parse-email-address com.acme.email::build-index))

(defpackage :com.gigamonkeys.email-db
  (:use :common-lisp :com.gigamonkeys.text-db)
  (:import :com.acme.email :parse-email-address))

(defpackage :com.acme.text
  (:use :common-lisp))

(defpackage :com.gigamonkeys.email-db
  (:use
   :common-lisp
   :com.gigamonkeys.text-db
   :com.acme.text)
  (:import :com.acme.email :parse-email-address)
  (:shadow :build-index))

(defpackage :com.gigamonkeys.email-db
  (:use
   :common-lisp
   :com.gigamonkeys.text-db
   :com.acme.text)
  (:import :com.acme.email :parse-email-address)
  (:shadow :build-index)
  (:shadowing-import :com.gigamonkeys.text-db :save))

(defpackage :foolib
  (:use :common-lisp))

(defun foolib::foo () t)

(defpackage :foolib
  (:use :common-lisp)
  (:export foolib::foo))

(foo)

(use-package :foolib)

Session transcript

Below is the transcript of the test session. The code apparently works as expected, including the intentional errors Undefined car of form and Package XCL-USER using FOOLIB results in name conflicts for symbols: FOO.

2/8> (eql ':foo :foo)
T
2/9> 

2/9> (symbol-name :foo)
"FOO"
2/10> 

2/10> (eql '#:foo '#:foo)
NIL
2/11> 

2/11> (gensym)
#:G30
2/12> 

2/12> *package*
#<Package XCL-USER>
2/13> 
common-lisp:*package*
#<Package XCL-USER>
2/14> 
cl:*package*
#<Package XCL-USER>
2/15> 
(defvar *x* 10)
*X*
2/16> 

2/16> *x*
10
2/17> 
:a
:A
2/18> 
keyword:a
:A
2/19> 
(eql :a keyword:a)
T
2/20> 

2/20> (defpackage :com.gigamonkeys.email-db
  (:use :common-lisp))
"COM.GIGAMONKEYS.EMAIL-DB"
2/21> 

2/21> (defpackage "COM.GIGAMONKEYS.EMAIL-DB"
  (:use "COMMON-LISP"))
"COM.GIGAMONKEYS.EMAIL-DB"
2/22> 

2/22> (in-package :com.gigamonkeys.email-db)
#<Package COM.GIGAMONKEYS.EMAIL-DB>
2/23> 

2/23> (defun hello-world () (format t "hello from EMAIL-DB package~%"))
HELLO-WORLD
2/24> 

2/24> (hello-world)
hello from EMAIL-DB package
NIL
2/25> 

2/25> (in-package :xcl-user)
#<Package XCL-USER>
2/26> 

2/26> (defun hello-world () (format t "hello from XCL-USER package~%"))
HELLO-WORLD
2/27> 

2/27> (hello-world)
hello from XCL-USER package
NIL
2/28> 

2/28> (defpackage :com.gigamonkeys.text-db
  (:use :common-lisp))
"COM.GIGAMONKEYS.TEXT-DB"
2/29> 

2/29> (defun com.gigamonkeys.text-db::open-db () t)
COM.GIGAMONKEYS.TEXT-DB::OPEN-DB
2/30> 

2/30> (defun com.gigamonkeys.text-db::save () t)
COM.GIGAMONKEYS.TEXT-DB::SAVE
2/31> 

2/31> (defun com.gigamonkeys.text-db::store () t)
COM.GIGAMONKEYS.TEXT-DB::STORE
2/32> 

2/32> (defpackage :com.gigamonkeys.text-db
  (:use :common-lisp)
  (:export com.gigamonkeys.text-db::open-db   
           com.gigamonkeys.text-db::save
           com.gigamonkeys.text-db::store))
"COM.GIGAMONKEYS.TEXT-DB"
2/33> 

2/33> (defpackage :com.gigamonkeys.email-db
  (:use :common-lisp :com.gigamonkeys.text-db))
"COM.GIGAMONKEYS.EMAIL-DB"
2/34> 

2/34> (defpackage :com.acme.email
  (:use :common-lisp))
"COM.ACME.EMAIL"
2/35> 

2/35> (defun com.acme.email::parse-email-address () t)
COM.ACME.EMAIL::PARSE-EMAIL-ADDRESS
2/36> 

2/36> (defun com.acme.email::build-index () t)
COM.ACME.EMAIL::BUILD-INDEX
2/37> 

2/37> (defpackage :com.acme.email
  (:use :common-lisp)
  (:export com.acme.email::parse-email-address com.acme.email::build-index))
"COM.ACME.EMAIL"
2/38> 

2/38> (defpackage :com.gigamonkeys.email-db
  (:use :common-lisp :com.gigamonkeys.text-db)
  (:import :com.acme.email :parse-email-address))
"COM.GIGAMONKEYS.EMAIL-DB"
2/39> 

2/39> (defpackage :com.acme.text
  (:use :common-lisp))
"COM.ACME.TEXT"
2/40> 

2/40> (defpackage :com.gigamonkeys.email-db
  (:use
   :common-lisp
   :com.gigamonkeys.text-db
   :com.acme.text)
  (:import :com.acme.email :parse-email-address)
  (:shadow :build-index))
"COM.GIGAMONKEYS.EMAIL-DB"
2/41> 

2/41> (defpackage :com.gigamonkeys.email-db
  (:use
   :common-lisp
   :com.gigamonkeys.text-db
   :com.acme.text)
  (:import :com.acme.email :parse-email-address)
  (:shadow :build-index)
  (:shadowing-import :com.gigamonkeys.text-db :save))
"COM.GIGAMONKEYS.EMAIL-DB"
2/42> 

2/42> (defpackage :foolib
  (:use :common-lisp))
"FOOLIB"
2/43> 

2/43> (defun foolib::foo () t)
FOOLIB::FOO
2/44> 

2/44> (defpackage :foolib
  (:use :common-lisp)
  (:export foolib::foo))
"FOOLIB"
2/45> 

2/45> (foo)
Undefined car of form
FOO

2/46> 

2/46> (use-package :foolib)
Package XCL-USER using FOOLIB results in name conflicts for symbols:
FOO 
NIL
2/47>