Nix has two kinds of problems: the language and the interface. They can solve interface problems, but the Nix language is a tumor that won't be easily removed. The problem is that Nix the language is the worst of all worlds: - You can't print anything because the language is lazy. Forcing any values to print them can and will result in random operations happening on your store. You can never know which values are saf…
`lib.deepSeq` can be used to fully evaluate a thunk. `lib.trace` can be used to emit a log each time a value gets evaluated.
> - Everything in Nix is recursive, datastructures contain copies of themselves as hacks to avoid building proper APIs. So again, you can't print anything, even if you're sure that printing the object won't do something crazy to your store.
derivations are just a dictionary of information, passed to a `derivation` function; which communicates to nix that it should be built/realised. There is a minimal API for a derivation, which is just `name` and `builder` in attr set. In general, the builder will refer to script which may have additional levers. For example, `stdenv.mkDerivation` also expects a src.
> - There are almost no APIs and no uniformity in Nix. Packages are given total freedom to do anything. The Python ecosystem works totally differently from the Haskell one which works totally differently from the C++ one. It's insane. They use different datastructures, functions, etc. To do the same thing.
"Just because two things are similar, doesn't mean they're the same". I wouldn't expect building openssl to look similar to building ripgrep, a python package, or a node package. Each domain has it's own oddities. Python for example expects packages to be installed at `${prefix}/lib/python-${python.majorVersion}.${python.minorVersion}/site-package`
> - The Nix language has impossible error messages. You will get stuck. You can't view values and you can't get error messages. There's no moving forward from that unless you ask someone.
This has significantly improved with nix 2.4+. `--show-trace` will now show you an entire stack trace with files and line numbers.
> - Laziness in Nix is different from laziness in Haskell. In Haskell, it's mostly about performance improvements and some cool tricks here and there. In Nix, laziness fundamentally means something: you build up packages and you force them to install them.
For haskell, I think it was originally a side-effect of how they implemented the language. For nixpkgs, this is still important because nixpkgs is just a large dictionary (attr set). However, doing something like `nix-shell -p cargo`, will avoid having to evaluate all of nixpkgs, just what I need for cargo.
Also, nix doesn't build a package when it evaluates it. Building is done as part of realization (which many commands do implicitly).
https://book.divnix.com/ch04-02-realise-a-derivation.html
> - You cannot install Nix in your home account without root permissions (yes, there are hacks, but they break terribly). So Nix is actually less isolated and less portable than something like Anaconda!
This is because `/nix` needs to exist, and can't be a symlink. sudo only needs to be done once. user installs can be performed after that.
> - The commandline experience is terrible. Nothing makes any sense. Not the names of the tools. Not their arguments. Why sometimes something is a binary and other times it's a mode of another tool, etc.
The `nix-*` commands are a carry-over from the phd days of nix. Where they are reflect closely to the underlying nix machinery. The nix 2.0 `nix ` cli tries to better reflect "user scenarios", but still kind of a WIP. So I agree, cli is probably one of the weakest aspects of nix right now.
> - In exchange for making some hard things easy, Nix makes a lot of easy things very hard. Sure, it will manage an isolated environment. But, now you want a package from pip that isn't in Nix? There is literally no way for you to figure out how to do this, you need to find a tutorial online, hope it's up to date enough to work, and follow it step by step. And.. there's a good chance you misunderstood what the tutorial was doing and won't have the correct environment at the end.
Depends on the toolchain. Rust and Go builds are almost trivial to support now. Python and other ecosystems which rely on a lot of impure behavior will have the most impedance mismatch with nix.
Mixing a nix python packages with venv is described here: https://nixos.org/manual/nixpkgs/stable/#how-to-consume-pyth...