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Comment by salsa_catsup

2 days ago

Is Racket the Lisp where I wanted to write keywords like `foo:` or `:foo`, but they went with something like `'#:foo`, which ruined keyword syntax for me?

8 comments

salsa_catsup

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soegaard  1 day ago

Fear not, you can make `#%top` and `#:app` rewrite `foo:` to `#:foo`.

FWIW choosing `#:foo` over, say, `foo:` was due to backwards compatibility. In Scheme and Racket `foo:` is a legal identifier, so there might have been programs that stopped working, if `foo:` suddenly was a keyword.

tmtvl  2 days ago

I don't know about Racket, but I do know Guile does that and I kind of prefer it as a way to reduce syntax (because the number sign is syntax already for most Lisps as the marker for a vector, and it's also used to bring functions into the symbol namespace in a Lisp-2) by freeing the colon.

  • everforward  2 days ago

    Do they do something neat with the colon? I do prefer the shorter keyword syntax, at least in Clojure because of how common they are.

    Clojure tends to use them very heavily though, and last I looked it seemed like Racket used more lists (as a matter of community preference, not forced by the language).

    • tmtvl  1 day ago

      A colon in Guile is just a regular character. For example:

        (define abc:def 3)
  (define :ghi 4)
  (* abc:def :ghi) ; => 12

      In Common Lisp a colon is a package separator, with an optional package which defaults to the keyword package if not given.

        (eq :foo keyword:foo) ; => t

      I don't know about Clojure or Racket because I don't know much about Clojure or Racket. I know Clojure differs in various ways where syntax is concerned to Common Lisp or Scheme (I do like the idea of using square brackets to visually indicate that a collection of atoms may not represent a function call, I hate the idea of the comma being a whitespace character) and that Racket has different languages (though I don't know what that means in practise).

      That said, I don't quite know what to think of your third sentence:

      > Clojure tends to use them very heavily though, and last I looked it seemed like Racket used more lists

      I suppose them refers to keywords? But Racket uses more lists compared to how much Clojure uses keywords? As lists have more uses than keywords that seems likely, though as I said: I don't know anything about Clojure or Racket apart from Racket once being called PLT Scheme.

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