Eitaro Fukamachi presents CL21, a redesign of Common Lisp for the 21st century. CL21 aims to improve Common Lisp's consistency, expressiveness, compatibility, and efficiency. It focuses on simplifying naming conventions, removing unnecessary symbols, and making the language more suitable for modern use while maintaining 100% compatibility with Common Lisp code and libraries. The project is still in development with discussions ongoing about final syntax and standard library decisions. CL21 hopes to make Lisp a premier language for prototyping by building on Common Lisp's strengths.

1. Shibuya.lisp Tech Talk #8 Eitaro Fukamachi
Redesigning Common Lisp

2. Thank you for coming.

3. I’m Eitaro Fukamachi
@nitro_idiot fukamachi

4. (and 'web-application-developer
'common-lisper)

5. GitHub product languages
Others
Clojure
Perl
Emacs Lisp
JavaScript
Common Lisp

6. GitHub product languages

7. I ♥ Common Lisp

8. because…

9. Common Lisp is
the most powerful, expressive
and fast language ever.

10. Common Lisp is damn powerful
• First class functions + lexical closures
• Object system + multiple dispatch
• Metaobject protocol

11. Common Lisp is expressive
• Reader macros
• Macros

12. Common Lisp is fast
• (Optional) type declaration
• Inlining functions
• Compiler macros
• Disassembler included
• Free high-performance implementation

13. Common Lisp is
the most powerful, expressive
and fast language ever.

14. = GOD LANGUAGE

15. So, here is a question.

16. Is Common Lisp
perfect?

17. Is Common Lisp
successful?

18. Is Common Lisp
attractive to young people?

19. ……………..

20. “well…”

21. Common Lisp is
not sophisticated
• too-long-wordy-name-for-common-macros
• append & nconc
• elt vs aref vs nth
• getf vs gethash
• map?? mapc?? dolist?? loop??
• Functional vs Procedual

22. It’s because of the origin.

23. Portability
8 Goals of
standardising Common Lisp
Commonality
Consistency
Expressiveness
Compatibility
Efficiency
Power
Stability
from Common Lisp the Language

24. Common Lisp is a compound of
MacLISP, Zetalisp,
Spice Lisp, NIL and S-1 Lisp.

25. Common Lisp was designed for
MacLISP, Zetalisp,
Spice Lisp, NIL and S-1 Lisp
users, not us.

26. Besides,
Common Lisp is old.

27. Common Lisp = 30 years old
Ruby = 19 years old
JavaScript = 19 years old
Clojure = 7 years old

28. Common Lisp was designed for
people 30 years ago.

29. But it doesn’t mean
Common Lisp is obsolete.

30. Common Lisp is
the most powerful, expressive
and fast language ever.

31. Common Lisp is the best one,
but I’m still not fulfilled in it.

32. CLtL3? Almost hopeless.

33. Let’s redesign Common Lisp
for the 21st century
by ourselves.

34. “Common Lisp
for the 21st century”

35. “CL21”

36. What is CL21?
• (One of) the next generation of
Common Lisp
• Bases on Common Lisp
• Designed for us
• Actual implementation
(not only discussions)

37. Portability
8 Goals of
standardising Common Lisp
Commonality
Consistency
Expressiveness
Compatibility
Efficiency
Power
Stability
from Common Lisp the Language

38. Consistency
Expressiveness
4 Goals of CL21
Compatibility
Efficiency

39. Goal 1: Consistency

40. Consistency of CL21
• Naming convention
• Argument order

41. Consistency of CL21
Common Lisp
(reverse '(1 2 3))
(nreverse '(1 2 3))
!
(append '(1 2 3) '(a b c))
(nconc '(1 2 3) '(a b c))

42. Consistency of CL21
CL21
(reverse '(1 2 3))
(nreverse '(1 2 3))
!
(append '(1 2 3) '(a b c))
(nappend '(1 2 3) '(a b c))

43. Consistency of CL21
Common Lisp
(getf person :name)
(gethash :name person-hash)

44. Consistency of CL21
CL21
(getf person :name)
(gethash person-hash :name)

45. Goal 2: Expressiveness

46. Expressiveness of CL21
• Specific vs Generic
• Delete useless symbols

47. Expressiveness of CL21
• Specific vs Generic
• Delete useless symbols

48. Expressiveness of CL21
• Specific vs Generic
• Delete useless symbols

49. Expressiveness of CL21
• Specific vs Generic
• Delete useless symbols
(ed “~/.sbclrc”)

50. Expressiveness of CL21
• Specific vs Generic
• Delete useless symbols
Are you crazy????
(ed “~/.sbclrc”)

51. Expressiveness of CL21
Common Lisp
(append '(1 2 3) '(a b c))
(concatenate 'vector #(1 2 3) '())
(concatenate 'string "Hello, " name)

52. Expressiveness of CL21
CL21
(append '(1 2 3) '(a b c))
(append #(1 2 3) '())
(append "Hello, " name)

53. Expressiveness of CL21
Common Lisp
(mapcar #'1+ '(1 2 3))
(map 'vector #'1+ #(1 2 3))

54. Expressiveness of CL21
CL21
(map #'1+ '(1 2 3))
(map #'1+ #(1 2 3))

55. Expressiveness of CL21
Common Lisp
(format nil "Hello, World!~%")
(format nil "Hello, ~A~%" name)

56. Expressiveness of CL21
CL21
"Hello, World!n"
#"Hello, ${name}n"

57. Expressiveness of CL21
Common Lisp
(parse-integer "1984")
(symbol-name 'alien-technology)

58. Expressiveness of CL21
CL21
(coerce "1984" 'integer)
(coerce 'alien-technology 'string)

59. Expressiveness of CL21
(ql:quickload :cl-ppcre)
(use-package :cl-ppcre)
!
(scan-to-strings "^(d{4})-(d{2})-(d{2})$"
"2014-01-23")
(regex-replace-all "a" "Eitaro Fukamachi" "α"
:preserve-case nil)
Common Lisp

60. Expressiveness of CL21
CL21
(use-package :cl21.re)
!
(#/^(d{4})-(d{2})-(d{2})$/ "2014-01-23")
(re-replace #/a/ig "Eitaro Fukamachi" "α")

61. Expressiveness of CL21
CL21
!
(use-package :cl21.re)
!
(#/^(#/^(d{4})-(d{2})-(d{2})$/
"2014-01-23")
(re-replace #/a/ig
"Eitaro Fukamachi" "α")

62. Expressiveness of CL21
CL21
!
(use-package :cl21.re)
!
(#/^(#/^(d{4})-(d{2})-(d{2})$/
"2014-01-23")
(re-replace #/a/ig
"Eitaro Fukamachi" "α")
Appliable Regex literal

63. Expressiveness of CL21
Common Lisp
(ql:quickload :clazy)
(use-package :clazy)
!
(defun fib-seq ()
(labels ((rec (a b)
(clazy:lazily (cons a
(rec b (+ a b))))))
(rec 0 1)))
!
(head (tail (tail (tail (fib-seq)))))
(lazy-seq:take 5 (fib-seq))

64. Expressiveness of CL21
CL21
(use-package :cl21.lazy)
!
(defun fib-seq ()
(labels ((rec (a b)
(lazy-sequence (cons a
(rec b (+ a b))))))
(rec 0 1)))
!
(first (rest (rest (rest (fib-seq)))))
(elt (fib-seq) 3)
(subseq (fib-seq) 0 5)

65. Expressiveness of CL21
CL21
!
(use-package :cl21.lazy)
!
(defun fib-seq ()
(labels ((rec (a b)
Abstract sequence
(lazy-sequence
(cons a
(rec b (+ a b))))))
(rec 0 1)))
!
!
!
!
!
(first (rest (rest (rest (fib-seq)))))
(elt (fib-seq) 3)
(subseq (fib-seq) 0 5)

66. Expressiveness of CL21
CL21
!
(use-package :cl21.lazy)
!
(defun fib-seq ()
(labels ((rec (a b)
Abstract sequence
(lazy-sequence
(cons a
(rec b (+ a b))))))
(rec 0 1)))
!
!
!
!
!
(first (rest (rest (rest
(fib-seq)))))
(elt
(fib-seq) 3)
(subseq
(fib-seq) 0 5)
Builtin sequence functions
are available

67. Goal 3: Compatibility

68. Compatibility of CL21
• Written in Common Lisp
• 100% compatible with Common Lisp
• All CL libraries are available

69. Compatibility of CL21
(defsystem my-cl21-app
:defsystem-depends-on (:cl21)
:class :cl21-system
:components ((:file "src/myapp")))

70. Compatibility of CL21
(!
defsystem my-cl21-app
:defsystem-depends-on (:cl21)
:class :cl21-system
:components ((:file "src/myapp")))

71. Goal 4: Efficiency

72. Efficiency of CL21
• (less important in CL21, though)
• Generic methods are slow
• Compiler macros

73. Consistency
Expressiveness
4 Goals of CL21
Compatibility
Efficiency

74. Other topics: “syntax”

75. “syntax”
• CL21 has “syntax”
• “syntax” = readtable bound to a package

76. “syntax”
(defsyntax cl21.process
((## #`) #'run-process-reader))
!
(export-syntax 'cl21.process)
(use-package :cl21.process)
!
#`ls -l /Users`

77. Other topics:
Standard libraries

78. Batteries included (?)
• cl21.re
• cl21.process
• cl21.lazy
• cl21.os

79. Remember
CL21 is 100% compatible
with Common Lisp

80. You see
how Common Lisp is
expressive and growable?

81. Current status

82. Current status
• Still in development
• No backward-compatibility guaranteed
• We’ll release in the 21st century
• Not settled discussions
• loop vs iterate vs series

83. WEB SITE:
cl21.org
!
GITHUB:
github.com/cl21/cl21

84. Make Lisp the Premier
Prototyping Language.
— Richard P. Gabriel “Worse Is Better”

85. Thanks.

86. EITARO FUKAMACHI
8arrow.org
@nitro_idiot fukamachi