3 ms·

> dynamic scoping Right you are. Even more horrible. The tcl language still has it!

School-Cotton 1y ago
So does emacs lisp, by default, although you can set it to lexical scope per-file (and it’s recommended to always do so).
eru 1y ago
I think EmacsLisp also does dynamic scoping. Or at least they used to about ten years ago. Not sure, if they fixed it?
jrapdx3 1y ago
Well, Tcl is kind of a mixture of scope rules. In some respects, e.g., within a proc, it's mainly a lexical environment, but of course dynamic scoping is introduced by commands like upvar/uplevel. FWIW Tcl programmers don't concern themselves very much with sorting out dynamic vs. lexical. In any case, Tcl programmers are careful to maximize static scoping. No doubt that's necessary to create reliable larger programs many of which have been written in Tcl.
geocar 1y ago
Dynamic scope/binding is super useful, but I do not agree tcl does it or does it well, because it's not just shadowing the closure environment (ha), or changing globals in a dynamic-wind. Perl's the only non-lisp I'm aware of that does dynamic binding well-enough to get the idea, but too many things just don't work: local *int = sub { return 69 }; print int("42"); is a particularly annoying one: You just can't do it. Other names might have better chances, e.g. package foo; sub int { 42 }; package main; sub a{local *foo::int = sub { return 69 };&b(@_);} sub b{goto \&foo::int}; print b("x"), a("x"), b("x"), a("x"); but this is a little unsatisfying.
- eru 1y ago
  > Perl's the only non-lisp I'm aware of that does dynamic binding well-enough to get the idea, [...] Well, Haskell does dynamic binding in the form of the Reader Monad. It's well received there.
  - geocar 1y ago
    Erm no. The point is I want to have the ability to make any variable dynamic, not just work with a global variable that is really a getter.
    - eru 1y ago
      The reader monad doesn't need to be global. But yeah, by that standard, Haskell implements both dynamic scoping and mutable state via getters and setters. (Though, of course, you can go all out on these via lenses.)

So does emacs lisp, by default, although you can set it to lexical scope per-file (and it’s recommended to always do so).

eru 1y ago

I think EmacsLisp also does dynamic scoping. Or at least they used to about ten years ago. Not sure, if they fixed it?

jrapdx3 1y ago

Well, Tcl is kind of a mixture of scope rules. In some respects, e.g., within a proc, it's mainly a lexical environment, but of course dynamic scoping is introduced by commands like upvar/uplevel. FWIW Tcl programmers don't concern themselves very much with sorting out dynamic vs. lexical. In any case, Tcl programmers are careful to maximize static scoping. No doubt that's necessary to create reliable larger programs many of which have been written in Tcl.

geocar 1y ago

Dynamic scope/binding is super useful, but I do not agree tcl does it or does it well, because it's not just shadowing the closure environment (ha), or changing globals in a dynamic-wind. Perl's the only non-lisp I'm aware of that does dynamic binding well-enough to get the idea, but too many things just don't work: local *int = sub { return 69 }; print int("42"); is a particularly annoying one: You just can't do it. Other names might have better chances, e.g. package foo; sub int { 42 }; package main; sub a{local *foo::int = sub { return 69 };&b(@_);} sub b{goto \&foo::int}; print b("x"), a("x"), b("x"), a("x"); but this is a little unsatisfying.

eru 1y ago
> Perl's the only non-lisp I'm aware of that does dynamic binding well-enough to get the idea, [...] Well, Haskell does dynamic binding in the form of the Reader Monad. It's well received there.
- geocar 1y ago
  Erm no. The point is I want to have the ability to make any variable dynamic, not just work with a global variable that is really a getter.
  - eru 1y ago
    The reader monad doesn't need to be global. But yeah, by that standard, Haskell implements both dynamic scoping and mutable state via getters and setters. (Though, of course, you can go all out on these via lenses.)