forked from lix-project/lix
Robert Hensing
260c614762
**`Value` and `const`** These two deserve some explanation. We'll get to lists later. Values can normally be thought of as immutable, except they are are also the vehicle for call by need, which must be implemented using mutation. This circumstance makes a `const Value` a rather useless thing: - If it's a thunk, you can't evaluate it, except by copying, but that would not be call by need. - If it's not a thunk, you know the type, so the method that acquired it for you should have returned something more specific, such as a `const Bindings &` (which actually does make sense because that's an immutable span of pointers to mutable `Value`s. - If you don't care about the type yet, you might establish the convention that `const Value` means `deepSeq`-ed data, but this is hardly useful and not actually as safe as you would supposedly want to trust it to be - just convention. **Lists** `std::span` is a tuple of pointer and size - just what we need. We don't return them as `const Value`, because considering the first bullet point we discussed before, we'd have to force all the list values, which isn't what we want. So what we end up with is a nice representation of a list in weak head normal form: the spine is immutable, but the items may need some evaluation later. |
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| .github | ||
| config | ||
| contrib | ||
| doc | ||
| m4 | ||
| maintainers | ||
| misc | ||
| mk | ||
| perl | ||
| scripts | ||
| src | ||
| tests | ||
| unit-test-data | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .gitignore | ||
| .version | ||
| boehmgc-coroutine-sp-fallback.diff | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| default.nix | ||
| docker.nix | ||
| flake.lock | ||
| flake.nix | ||
| local.mk | ||
| Makefile | ||
| Makefile.config.in | ||
| precompiled-headers.h | ||
| README.md | ||
| shell.nix | ||
Nix
Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. Please refer to the Nix manual for more details.
Installation and first steps
Visit nix.dev for installation instructions and beginner tutorials.
Full reference documentation can be found in the Nix manual.
Building And Developing
See our Hacking guide in our manual for instruction on how to set up a development environment and build Nix from source.
Contributing
Check the contributing guide if you want to get involved with developing Nix.
Additional Resources
License
Nix is released under the LGPL v2.1.