yieldpattern VS trivia

I’m writing a TypeScript package for pattern matching by using generator functions.

https://github.com/RoyalIcing/yieldpattern

It’s amazing to me how much pattern matching, well, matches how I think. A conditional if statement means I have to explicitly read properties off an object or inspect an array to check for what I want. Whereas pattern matching means asking ‘I want something that looks like this’ and do the work for me.

I've used it. :)

https://github.com/guicho271828/trivia/issues/108

You can see it, for instance, in the Trivia library ( https://github.com/guicho271828/trivia/blob/master/level0/impl.lisp ): the macro match0 is a thin wrapper around the function parse-patterns, and this, in turn, calls the function make-pattern-predicate which performs the recursive destructuring of patterns.

I can agree it's not the same, but what's the point? A more interesting disagreement is that I wouldn't say it's a downside (though yes, there are tradeoffs). Especially in Current Year when open source is fashionable and pretty much every language has a package manager to make pulling in or swapping out dependencies pretty easy, I don't see the issue. It's also interesting to note that of all the things Clojure did to "fix" shortcomings of past languages with a more opinionated (and often more correct I'll admit) design philosophy that users are forced to use (even when it's not more correct), infix-math-out-of-the-box wasn't one of them. I don't think that specifically really hurt Clojure adoption. (But of course Clojure is reasonably extensible too so it also has a macro package to get the functionality, though it's more fragile especially around needing spaces because it's not done with reader macros.)

I've brought the library up many times because CL, unlike so many other languages, really lets you extend it. Want a static type system? https://github.com/coalton-lang/coalton/ Want pattern matching? No need to wait for PEP 636, https://github.com/guicho271828/trivia/ If all that keeps someone from trying CL, or from enjoying it as much as they could because of some frustration or another, due to lacking out of the box, chances are it is available through a library.

Great libraries like trivia, iterate/for/alternative loop libraries, alexandria, and a hundred others. Common Lisp is a general purpose programming language with good support for ffi, working with files, databases, images, audio, etc. Just skim awesome-cl if you haven't. You could argue this doesn't have to do with the language, but a lot of these libraries are so good (or even possible) in part because of language features elisp does not have.

> After much deliberation, the Python Steering Council is happy to announce that we have chosen to accept PEP 634, and its companion PEPs 635 and 636, collectively known as the Pattern Matching PEPs

This is why I'm still enamored with Lisp. One doesn't wait around for the high priests to descent from their lofty towers of much deep pontification and debate with shiny, gold tablets inscribed with how the PEPs may be, on behalf of the plebes. One just adds new language feature themselves, eg. pattern matching[1] and software transactional memory[2].

1. https://github.com/guicho271828/trivia

2. https://github.com/cosmos72/stmx

The source is impressively simple! Good job!

I have been implementing a pattern matcher for scheme based on the Balland pattern optimized, and every time I see pattern matchers for python I always get the feeling that the code you are replacing have to be truly awful for the rather contrived pattern matching syntax to be a net win. Compare any of the python pattern matchers to something like trivia in Common Lisp [0] and you see what I mean.

How do people use the python pattern matchers? I am genuinely curious. One benefit that I see is that you can build patterns at run-time which could be useful.

[0]: https://github.com/guicho271828/trivia/wiki/Type-Based-Destr...