4 ms·

I've always wondered why that was added. It feels to me against the idiom (argot?) of any lisp. It's not composable either. (0 . < . x . < . 12) re

I've always wondered why that was added. It feels to me against the idiom (argot?) of any lisp. It's not composable either. (0 . < . x . < . 12) read-syntax: illegal use of `.` Typing those extra '.'s gets annoying very quickly too.

srcreigh 5y ago
My guess is Racket/PLT scheme's history as a language for teaching programming to students. Racket has some other things that are non-lispy. Support for alternate (maybe non-SEXP) syntax readers and for loops come to mind. At least it's all simple. Sometimes terrifyingly simple, but simple. They're useful too. Non-SEXP reader could be used to create a non-infix dialect of Racket. Loop macros like for/or can be used as a more ergonomic way than recursive functions to walk a list to find/transform one of its elements.
kazinator 5y ago
MacLisp had an extended dot notation similar to this for hunks: https://www.maclisp.info/pitmanual/hunks.html https://www.maclisp.info/pitmanual/hunks.html
soegaard 5y ago
It was an experiment - I think the general consensus is that it was a bad idea. The double dot notation is mostly used for inequalites: (x . < . 3) instead of (< x 3) and for function contracts: (any . -> . boolean?) instead of (-> any boolean?)