| let | |
| pkgs = import <nixpkgs> {}; | |
| lib = pkgs.lib; | |
| allOptions = (import <nixpkgs/nixos> {}).options; | |
| # ** some helpers | |
| # Like mapAttrs, but if `null` is returned from the mapping function, | |
| # the element is removed from the attrset. | |
| # |
This guide takes you through your first steps with the Nix package manager.
While NixOS is a Linux distribution based on Nix, you can install Nix on other Linux distributions, MacOS and Windows via WSL using the install script from our website:
curl -L https://nixos.org/nix/install | sh
This is a collection of the things I believe about software development. I have worked for years building backend and data processing systems, so read the below within that context.
Agree? Disagree? Feel free to let me know at @JanStette. See also my blog at www.janvsmachine.net.
Keep it simple, stupid. You ain't gonna need it.
| -- | Our main engine for naming a value, then we can prove properties about a named value. | |
| {-# LANGUAGE ExistentialQuantification #-} -- Used for SomeNamed. | |
| {-# LANGUAGE PatternSynonyms #-} -- Used for the Name pattern. | |
| {-# LANGUAGE ViewPatterns #-} -- Used for the Name pattern. | |
| {-# LANGUAGE RankNTypes #-} -- Used for withName. | |
| module Named ( Named, pattern Name, forgetName, withName, someNamed, SomeNamed(..) ) where | |
| -- | Give a generated type-level name to any value. |
Someone asked whether or not acid-state was production ready. I shared my experiences:
parsonsmatt [11:32 AM] @nikolap it's used by cardano-wallet and Hackage. Based on my experience with acid-state, I'd say it is not a good choice for production data storage. For local desktop apps, SQLite is a much better choice, and for real production apps, Postgresql is king.
parsonsmatt [11:44 AM] acid-state did not have a test suite, at all, until I implemented the very first tests (for TemplateHaskell code generation) earlier this year. It has picked up some tests since then, but I'm still not confident in it's correctness.
It claims to be resilient to unplugging the power cord, but I doubt that, as it's not resilient to Ctrl-C: acid-state/acid-state#79
nix-channel and ~/.nix-defexpr are gone. We'll use $NIX_PATH (or user environment specific overrides configured via nix set-path) to look up packages. Since $NIX_PATH supports URLs nowadays, this removes the need for channels: you can just set $NIX_PATH to e.g. https://nixos.org/channels/nixos-15.09/nixexprs.tar.xz and stay up to date automatically.
By default, packages are selected by attribute name, rather than the name attribute. Thus nix install hello is basically equivalent to nix-env -iA hello. The attribute name is recorded in the user environment manifest and used in upgrades. Thus (at least by default) hello won't be upgraded to helloVariant.
@vcunat suggested making this an arbitrary Nix expression rather than an attrpath, e.g. firefox.override { enableFoo = true; }. However, such an expression would not have a key in the user environment, unlike an attrpath. Better to require an explicit flag for this.
TBD: How to deal with search path clashes.
| { pkgs ? import (builtins.fetchTarball https://github.com/nixos/nixpkgs-channels/archive/nixos-unstable.tar.gz) {} }: | |
| let | |
| yaml = ./stack.yaml; | |
| cabal2nix = "${pkgs.cabal2nix}/bin/cabal2nix --no-check --no-haddock"; | |
| in | |
| pkgs.writeScript "build.sh" '' | |
| export NIX_PATH=nixpkgs=${pkgs.path} | |
| resolver=$(awk '/resolver:/{print $2}' ${yaml} | sed 's,\.,_,g') |
This is taken directly from Figure 5.2 in http://nixos.org/~eelco/pubs/phd-thesis.pdf. It is presented here to be more directly linkable.
serialise(fso) = str("nix-archive-1") + serialise1(fso)
serialise1(fso) = str("(") + seralise2(fso) + str(")")
serialise2(type=Regular, exec, contents) =
str("type") + str("regular")
+ (
As configured in my dotfiles.
start new:
tmux
start new with session name:
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Responsive Design Testing</title> | |
| <style> | |
| body { margin: 20px; font-family: sans-serif; overflow-x: scroll; } | |
| .wrapper { width: 6000px; } | |
| .frame { float: left; } | |
| h2 { margin: 0 0 5px 0; } |