The * convention for list* and hash-set* is an ad-hoc, wiggly, underspecified "convention." I would claim the naming of those functions as an historical accident, and shouldn't limit one from using * as primes. -Ian
----- Original Message ----- From: "Jon Zeppieri" <[email protected]> To: "J. Ian Johnson" <[email protected]> Cc: "robby" <[email protected]>, "users" <[email protected]> Sent: Thursday, January 8, 2015 3:55:08 PM Subject: Re: [racket] Racketrivia: Using ' as an identifier suffix I'm under the impression that * usually indicates some kind of pluralization or Kleene star-esque behavior. On Thu, Jan 8, 2015 at 3:53 PM, J. Ian Johnson <[email protected]> wrote: > Indeed, I tried it for a while and didn't like it. I use * instead of ' for > primes in my code. I think that's pretty common practice. > -Ian > > ----- Original Message ----- > From: "robby" <[email protected]> > To: "Jon Zeppieri" <[email protected]> > Cc: "users" <[email protected]> > Sent: Thursday, January 8, 2015 3:45:55 PM > Subject: Re: [racket] Racketrivia: Using ' as an identifier suffix > > That's a scary convention. It's hard for humans to see the difference! > > On Thu, Jan 8, 2015 at 2:32 PM, Jon Zeppieri <[email protected]> wrote: >> You can use the unicode prime character (′) as a suffix. In DrRacket, >> you can type that as \prime followed by ctrl-\. It would be a lot >> nicer to map it to a simple key combo like λ is, >> >> -Jon >> >> >> On Thu, Jan 8, 2015 at 3:15 PM, Greg Hendershott >> <[email protected]> wrote: >>> So Haskell conventionally uses ' as a suffix, prime. From what I've >>> seen, Scheme and Racket tend to use * instead. >>> >>> At some point I "learned" that you cannot use ' as a suffix in Racket. >>> >>> Today I tried again, and was surprised to see that it works... somewhat. >>> >>> $ racket >>> Welcome to Racket v6.1.1.6. >>> -> (define x' 42) >>> -> x' >>> 42 >>> -> (+ x' 10) >>> '(+ x '10) >>> -> (+ 10 x') >>> ; readline-input:4:8: read: unexpected `)' >>> -> (+ 10 x' ) >>> ; readline-input:5:8: read: unexpected `)' >>> >>> >>> 0. It turns out x' _is_ a valid identifier, and it self-evaluates just >>> fine. Interesting. >>> >>> 1. I don't understand why (+ x' 10) evaluates not to 52, and not even >>> an error, but... '(+ x '10). WAT. >>> >>> 2. Less surprising to me is that (+ 10 x') and even (+ 10 x' ) are >>> errors. But actually, I wonder why the reader (or lexer?) couldn't >>> handle ' followed by a character that can't be part of an identifier? >>> >>> >>> p.s. I'm not proposing this would be a great suffix style to use. >>> Quick, distinguish x' from 'x ! And don't type one when you mean the >>> other! I get that. Even so, I'm curious. >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
