Marko Rauhamaa writes: > Rustom Mody: > > > On Saturday, May 10, 2014 2:39:31 PM UTC+5:30, Steven D'Aprano wrote: > >> > >> Personally, I don't imagine that there ever could be a language > >> where variables were first class values *exactly* the same as > >> ints, strings, floats etc. > > > > [...] > > > > What you mean by *exactly* the same mean, I am not sure... > > Lisp variables (symbols) are on an equal footing with other objects. > IOW, lisp variables are objects in the heap.
Only some, or only in quite old or special members of the family. But yes, I suppose when Lisp was still LISP, it was the kind of language that Steven fails to imagine in the quotation above. Variables really were symbols, which still are objects that can be passed around and stored in data structures. Or maybe not - wasn't the essential binding component (originally an "association list", later a more abstract "environment", called "namespace" in Python culture) separate from the symbol even then? Global bindings aside. But default in Common Lisp is lexical binding, and Scheme has only lexical bindings. An ordinary lexical variable is not an object in any reasonable sense that I can see. (let ((f (let ((x 3)) (lambda () x)))) ;; The binding of x is still relevant here but not in scope and not ;; accessible through the symbol x (funcall f)) ;==> 3 # That's (lambda f : f())((lambda x : (lambda : x))(3)) #=> 3 # Roughly, f = (lambda x : (lambda : x))(3) ; f() #=> 3 -- https://mail.python.org/mailman/listinfo/python-list
