3 ms·
Then I'm surprised that it allows the user to define functions and macros.
by lispm 8y ago
Then I'm surprised that it allows the user to define functions and macros.
- didibus 8y agoI think most schemes also don't have reader macros. How often do you actually use them in CL? I feel reader macros have the problem that it modifies/extend the foundational syntax. And that can become overloaded really quickly. Normal macros can change evaluation semantics, but not the fundamental syntax. Which makes it easier to navigate and understand in general. Also, reader macros are pretty hard to write in comparison. Racket has a nice take on them though. Making them more like all new programming grammars, and defining your dialect per file. Even there though, most alternate syntax is for research or fun mostly.
- lispm 8y ago> I think most schemes also don't have reader macros. Scheme even has a fixed syntax in the RnRS reports. Lisp does not have that. > Also, reader macros are pretty hard to write in comparison. Not really. One just reads things from a stream and returns an s-expression. > I feel reader macros have the problem that it modifies/extend the foundational syntax That's a feature. The main purpose of user-written reader macros is to extend S-expressions to support literal syntax of new user-defined data types. There is nothing scary about it at all. > Racket has a nice take on them though. Making them more like all new programming grammars, and defining your dialect per file My Lisp Machine had that already in the 80s. It supported different language syntax - from various Lisp variants to Pascal, C and other languages. > Even there though, most alternate syntax is for research or fun mostly. On my Lisp Machine it was actually useful.
- didibus 8y ago> Scheme even has a fixed syntax in the RnRS reports. Lisp does not have that. Could you link to the RnRS in question? I'm curious. > Not really. One just reads things from a stream and returns an s-expression. I feel like if I agree to this, I also agree that pre-processors are easy to write and use. And that undermines the innovation and superiority of syntactic macros introduced by Lisp. > The main purpose of user-written reader macros is to extend S-expressions to support literal syntax of new user-defined data types. This is possible in Clojure as well. You can extend the language with new data literals. But they must begin with # + char(s) and respect the existing reader semantics, as they are processed as a syntactic macro, and not a lexical one. So you could add #queue[1 2 3] for example. But you couldn't add |1 2 3| > On my Lisp Machine it was actually useful. If only they'd still make those, and had improved its performance.
- lispm 8y ago> Scheme even has a fixed syntax in the RnRS reports. Lisp does not have that. https://schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-10.html#%_sec_7.1 https://schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-... > And that undermines the innovation and superiority of syntactic macros introduced by Lisp. They have a different purpose and operate on a different level. > respect the existing reader semantics This is an example of xapping data structure in *Lisp for for the Connection Machine {moe->"Oh, a wise guy, eh?" larry->"Hey, what's the idea?" curly->"Nyuk, nyuk, nyuk!"} > If only they'd still make those, and had improved its performance Nowadays it might be easier to use an emulator running the OS.
- didibus 8y ago> https://schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-10.html#%_sec_7.1 https://schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-... Sorry, maybe I'm not seeing it, but what part of that link describe lexical user definable reader macros in scheme? > {moe->"Oh, a wise guy, eh?" larry->"Hey, what's the idea?" curly->"Nyuk, nyuk, nyuk!"} Right, so in Clojure you could extend the reader and do: #xapping{moe "Oh, a wise guy, eh?" larry "Hey, what's the idea?" curly "Nyuk, nyuk, nyuk!"} As a data literal for xapping data structures.