14:11 <samth> griffinbyatt: what do you mean by "opaque"?

14:14 <griffinbyatt> samth: a base type only defined by its predicate, like it’s done via the #:opaque option here: https://docs.racket-lang.org/ts-reference/special-forms.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fprims..rkt%29._require%2Ftyped%29%29

14:14 <rudybot> https://teensy.info/q9onycPRQO

14:15 <samth> griffinbyatt: i guess i mean what do you need this for? in general, just using a struct should do everything you can do with an opaque type, and you can just not export the accessors

14:20 <griffinbyatt> Well, what I’m trying to do is a bit of a hack, and opaque types just seemed to be the best option. I’m trying to get more useful refinement types - e.g. I want a String that does not have the prefix “//“. Since typed racket’s refinements don’t allow that, I’m able to “fake” that behavior using an opaque type. `(Refine [n : String] (: n String-Without-Slash))`

20:10 <countvajhula> is there a standard function that evaluates to one of its arguments *by position*?

20:10 <countvajhula> e.g. (second-arg 5 6) ; => 6

21:23 <erkin> (if #f 5 6) => 6

21:55 <nisstyre> I was going to say const then I forgot racket doesn't let you do (f a b) as syntactic sugar for ((f a) b)

21:56 <nisstyre> and doesn't auto curry stuff obviously

22:35 <phillbush> Hello, I'm reading sicp and using racket. I'm new to lisp. Is there any library I can include in my racket files so I do not have to define accumulate every time, for example?

22:35 <phillbush> and other basic procedures like prime? and divides?

22:48 <bremner> oops, I was just going to answer