Hedgehog: an embedded Lisp in 20k | Hacker News Reader

Hedgehog: an embedded Lisp in 20k

hedgehog.oliotalo.fi

42 pointsgnosis7 comments

Their FOSDEM paper is a must read. A balanced and honest assessment of their little Lisp.

Customers have not cared whether Lisp is used or not. They have only cared about the results, and being able to change specifications with relative ease even after delivery and deployment has sometimes been a killer argument.

Indeed. Also interesting: Hedgehog lacks any mutation operator, because (paraphrasing) debugging issues caused by mutability over a slow serial line is not an effective use of time.

Also, it sounds like the way they implemented the standard library (at the Lisp level; functions used are part of the bytecode) brings implicit tree-shaking. Probably an excellent trade-off for embedded programming.

i had to google "tree shaking". i (now) think it means removing unneeded parts of the system for deployment (like compiler and debugger). but i don't understand how anything a library does can implicitly implement that. can you expand?

The way the system is set up (according to the paper), all functions appear as bytecode, i.e., the only stdlib functions added are those that are actually used. Probably not a big deal in most cases, but it sounds like a major bonus for embedded systems. For hedgehog, most of the system is only present at compile-time, under the assumption that it can do heavy compilation but will run on a weak system.

Also, thanks for all your blogging / commenting / etc. about OCaml over the years! Learned a ton. I'll buy you coffee or a pint if we ever cross paths.

OK, thanks. (Do you have the right person? I haven't used OCaml for years now. Anyway, if so, glad I could help...)

I think so...it was several years ago, when I was learning OCaml.

I can think of another programming language called Hedgehog, developed by Palantir Technologies: https://wiki.palantir.com/pflc/the-hedgehog-language.html

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