IParse VS coalton

Nice library with many features. But I do not always understand the focus on memory usage. I guess that the reason behind this is that less memory allocations, have a positive effect on execution times. In a parser, where you often have to compare identifiers, it is a good idea to put all strings for identifiers into a unique pointer with the help of a hash table.

In my interpreting parser [1] I use a hexa hash tree [2] for storing identifiers. It is not very memory efficient, but very fast. It turns every string (from the input buffer) into a unique pointer for that string pointing to a copy of the string. In this way comparing string (identifiers) is equivalent to comparing pointers.

The idea of the hexa hash tree is that is a tree where each node has sixteen child nodes. Which node is selected is based on a step wise evaluated hash function that first takes the lower four bytes of the string, and after reaching the end of the string, the higher four bytes of the string. The nodes often taken up more memory space than the strings themselves.

[1] https://github.com/FransFaase/IParse/

[2] https://github.com/FransFaase/IParse/blob/master/software/Id...

I wrote a tool that can process a number of MarkDown files with fragments of C code and put all those fragments in the right order to produce a file that can be compiled. It is grammar based and works with manipulating Abstract Syntax Trees, so I guess, it could be adapted for different programming languages. See: https://github.com/FransFaase/IParse#markdownc

Interesting. I have not looked into the code, but I wonder whether it is a compiler, or just an interpreter, e.g. it converts the grammar into some internal representation that is executed by an interpreter or virtual machine. I started worked on an interpreting parser in C many years ago. And later also made Java, C++ and JavaScript version of it. For the JavaScript implementation, see: https://fransfaase.github.io/ParserWorkshop/Online_inter_par... For the C++ version, see: https://github.com/FransFaase/IParse

I implemented an unparse function in IParse, which is not a parser generator, but a parser that interprets a grammar. See for example https://github.com/FransFaase/IParse/blob/master/software/c_... where symbols starting with a back slash are a kind of white space terminals during the unparse. For example, \inc stands for incrementing the indentation where \dec decrements it. The \s is used to indicate that at given location a space should be included.

It's still… not the same. In CL (and specially with SBCL), we get compile time (type) errors and warnings at the blink of an eye, when we compile a single function with a keystroke (typically C-c C-c in Slime).

And there's also been improvement, see Coalton for a ML on top of CL. (https://github.com/coalton-lang/coalton/)

For the parenthetically inclined among us, there's also an implementation in Coalton: <https://github.com/coalton-lang/coalton/tree/main/examples/t...>

Common Lisp has bad marketing (even OCaml has Twitch streamers and "influencers" now), and bad support for general editors, both of which make it a non-starter for most curious people who have an afternoon to try something. But behind all that is magnificent activity for those who got over the initial potential energy barrier. Just to give some examples:

1. SBCL, the most popular open source implementation of Lisp, is seeing potentially two new garbage collectors. One of them is a parallel collector written by a university student (!!) which blows my mind.

2. SBCL has better and better support for deploying Liwp as a C-compatible shared library, using SBCL-LIBRARIAN. It makes it play nicer with other applications in C and Python.

3. Coalton is another exciting development that allows a Haskell type system and "Lisp-1" functional programming in Common Lisp. That means type classes (or traits), something Lisp hasn't really had a proper notion of, and full type inference. Persistent sequences based off of RRB-trees were recently merged, and interestingly, they're implemented purely in Coalton [1]. That means Clojure-like seqs.

It's interesting to see users of Lisp generating the above ideas and libraries, not a special in-group of committees, "official" developers, etc.

[1] https://github.com/coalton-lang/coalton/blob/main/library/se...

Use an editor that auto-inserts parens and that indents the code correctly. Now nothing bad can happen. And the parens are used to edit code structurally.

re typing: Coalton brings Haskell-like typing on top of CL. https://github.com/coalton-lang/coalton/ Other lisps are typed: typed racket, Carp… and btw, SBCL's compiler brings some welcome type warnings and errors (unlike Python, for instance).

If you like type safety, this project would be perfect for using https://coalton-lang.github.io/ so your REPL supported Common Lisp out of the gate.

Agree that you can use types to express and prove logical properties via compiler; it can be a fun way to solve a problem though too much of it tends to frustrate coworkers. It's also not exactly "low cost"; here's an old quip I have in my quotes file:

"With Scala you feel smart having just got something to work in a beautiful way but when you look around the room to tell your clojure colleague how clever you are, you notice he left 3 hours ago and there is a post-it saying use a Map." --Daniel Worthington-Bodart

> On the contrary, they're still the most effective technique we've found for improving program correctness at low cost.

This is not borne out by research, such as there is any of any quality: https://danluu.com/empirical-pl/ The best intervention to improve correctness, if not already being done, is code review: https://twitter.com/hillelogram/status/1120495752969641986 This doesn't necessarily mean dynamic types are better, just that if static types are better, they aren't tremendously so to obviously show in studies, unlike code review benefit studies.

My own bias is in favor of dynamic types, though I think the way Common Lisp does it is a lot better than Python (plus Lisp is flexible enough in other ways to let static type enthusiasts have their cake and eat it too https://github.com/coalton-lang/coalton), and Python better than PHP, and PHP better than JS. Just like not all static type systems are C, not all dynamic type systems are JS. Untyped langs like assembly or Forth are interesting but I don't have enough experience.

I don't find the argument that valuable though, since I think just focusing on dynamic vs static is one of the least interesting division points when comparing languages or practices, and if we're trading experience takes I think Clojure's immutable-by-default prevents more bugs than any statically typed language that is mutable by default. It's not exactly a low cost intervention though, and when you really need to optimize you'll be encouraged by the profiler to replace some things with Java native arrays and so on. I don't think changing to static types would make a quality difference (especially when things like spec exist to get many of the same or more benefits) and would also not be a low cost intervention.

Last quip to reflect on. "What's true of every bug found in the field? ... It passed the type checker. ... It passed all the tests. Okay. So now what do you do? Right? I think we're in this world I'd like to call guardrail programming. Right? It's really sad. We're like: I can make change because I have tests. Who does that? Who drives their car around banging against the guardrail saying, "Whoa! I'm glad I've got these guardrails because I'd never make it to the show on time."" --Rich Hickey (https://www.infoq.com/presentations/Simple-Made-Easy/)

Coalton seems great, I love the idea. This issue seems problematic, though: https://github.com/coalton-lang/coalton/issues/84

> Lisps can be very flexible, but they usually lack static type safety, opening a wide and horrible door to run-time errors.

People should do basic research before writing something silly like this. Qualifying your statement with 'usually' is just a chicken sh*t approach. Common Lisp and Racket have optional strong typing, leaving the responsibility and choice to the developer. Common Lisp is great for implementing compilers. You also have thing like Typed Racket and Coalton. The latter is comletely statically typed ala MLTON

https://github.com/coalton-lang/coalton

Have you checked out Coalton? It allows static typing a la Haskell within Common Lisp. Fully interoperable with CL, including through SLIME etc.

I've not regretted using Common Lisp for large, professional projects. However, I started Coalton so that some parts of a Common Lisp project can have strong, static, strict types—reaping benefits of compile-time errors and increased efficiency when I need it, without having to rewrite everything.