4 ms·

>Yeah and the original cons cells had proper equality defined on them, which common lisp doesn't have. Substantiate your claims.

j-pb 6y ago
Sure! Most things in common lisp don't work with 'equal', which "poisons" the well so to speak. For example hash tables. (defparameter my-hash (make-hash-table)) (defparameter thy-hash (make-hash-table)) (setf (gethash 'one-entry my-hash) "one") (setf (gethash 'one-entry thy-hash) "one") (print (equal my-hash thy-hash)) NIL while in clojure every immutable datastructure you encounter in the std-lib or syntax has proper equality. (= {'one-entry "one"} {'one-entry "one"}) true To which McCarty had to say: > I considered it important to make these expressions obey the usual mathematical laws allowing replacement of expressions by expressions giving the same value.
- kazinator 6y ago
  Fixed in TXR Lisp: This is the TXR Lisp interactive listener of TXR 236. Quit with :quit or Ctrl-D on empty line. Ctrl-X ? for cheatsheet. 1> (defparm my (hash)) my 2> (defparm thy (hash)) thy 3> (set [my 'one-entry] "one") "one" 4> (set [thy 'one-entry] "one") "one" 5> (equal my thy) t 6> (set [thy 'two-entry] "two") "two" 7> (equal my thy) nil Or, briefly: 7> (equal #H(() (a b)) #H(() (a b))) t 8> (equal #H(() (a b)) #H(() (a c))) nil Also this: [1]> (equal '(1 2) '(1 2)) T [2]> (equal '(1 2) '(1 2.0)) NIL [3]> (equal #(1 2) #(1 2)) ;; oops, WTF? NIL [4]> 1> (equal '(1 2) '(1 2)) t 2> (equal '(1 2) '(1 2.0)) nil 3> (equal #(1 2) #(1 2)) t 4> (equal #(1 2) #(1 2.0)) nil
  - j-pb 6y ago
    Nice to hear, not CL tho ;P The (equal '(1 2) '(1 2.0)) is really a tricky one. Clojure also fails the (= 1 1.0) test. But I'm really not sure if that's a bad thing. I mean (= [1] #{1}) (an ordered vector and an unordered set) is also false, so it kinda makes sense to argue that distinct types are always distinct. However in clojure (= '(1) [1]) which I find a lot harder to defend It's caused by an automatic conversion to sequences which are then compared, and I think I might even add that one to the "warts" list.
  - lispm 6y ago
    Compare that with the rules of equality of Clojure: https://clojure.org/guides/equality https://clojure.org/guides/equality

j-pb 6y ago

Sure! Most things in common lisp don't work with 'equal', which "poisons" the well so to speak. For example hash tables. (defparameter my-hash (make-hash-table)) (defparameter thy-hash (make-hash-table)) (setf (gethash 'one-entry my-hash) "one") (setf (gethash 'one-entry thy-hash) "one") (print (equal my-hash thy-hash)) NIL while in clojure every immutable datastructure you encounter in the std-lib or syntax has proper equality. (= {'one-entry "one"} {'one-entry "one"}) true To which McCarty had to say: > I considered it important to make these expressions obey the usual mathematical laws allowing replacement of expressions by expressions giving the same value.

kazinator 6y ago
Fixed in TXR Lisp: This is the TXR Lisp interactive listener of TXR 236. Quit with :quit or Ctrl-D on empty line. Ctrl-X ? for cheatsheet. 1> (defparm my (hash)) my 2> (defparm thy (hash)) thy 3> (set [my 'one-entry] "one") "one" 4> (set [thy 'one-entry] "one") "one" 5> (equal my thy) t 6> (set [thy 'two-entry] "two") "two" 7> (equal my thy) nil Or, briefly: 7> (equal #H(() (a b)) #H(() (a b))) t 8> (equal #H(() (a b)) #H(() (a c))) nil Also this: [1]> (equal '(1 2) '(1 2)) T [2]> (equal '(1 2) '(1 2.0)) NIL [3]> (equal #(1 2) #(1 2)) ;; oops, WTF? NIL [4]> 1> (equal '(1 2) '(1 2)) t 2> (equal '(1 2) '(1 2.0)) nil 3> (equal #(1 2) #(1 2)) t 4> (equal #(1 2) #(1 2.0)) nil
- j-pb 6y ago
  Nice to hear, not CL tho ;P The (equal '(1 2) '(1 2.0)) is really a tricky one. Clojure also fails the (= 1 1.0) test. But I'm really not sure if that's a bad thing. I mean (= [1] #{1}) (an ordered vector and an unordered set) is also false, so it kinda makes sense to argue that distinct types are always distinct. However in clojure (= '(1) [1]) which I find a lot harder to defend It's caused by an automatic conversion to sequences which are then compared, and I think I might even add that one to the "warts" list.
- lispm 6y ago
  Compare that with the rules of equality of Clojure: https://clojure.org/guides/equality https://clojure.org/guides/equality