Comment by dragonwriter | Hacker News Reader

Comment by dragonwriter | Hacker News Reader

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> Yes, you can write functional style code, but you can write functional style code in C, C++, Java, Python, JS, Ruby, Common Lisp, Scheme, etc etc. That does not make any of these languages 'functional'.

Lisp-family languages (both CL and its immediate predecessors, and Scheme) for a long time were the textbook example of functional languages. The relatively novel (and still niche) attempt to redefine things so that only pure functional languages are “functional languages”, and particularly the people that insist on this usage as if it were firmly established and abuse those who don't conform to their preferred redefinition, is a bit annoying.

This is not correct, lisp operations on lists have always been to modify in place, with copying versions added later. The technology did not exist to do functional programming efficiently enough (and to some extent that technology still does not exist generally).

Simply false. For example, LISP 1.5 manual had this definition for UNION:

  (union (lambda (x y) (cond ((null x) y) ((member
         (car x) y) (union (cdr x) y)) (t (cons (car x)
         (union (cdr x) y))))))

It had a MAPLIST (today called MAPCAR):

  maplist[x;fn]=[null[x]->NIL;
                 t->cons[fn[x];maplist[cdr[x];fn]]]

Or APPEND:

  append[x;y] = [null[x] -> y; T -> cons[car[x]; append[cdr[x];y]]]

Et cetera. Sure, it also had, say, NCONC. But it had these operators and style from the beginning, not surprisingly, as Lisp came from lambda calculus.

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