snowfall-lib/lib/default.nix
2022-09-07 17:06:33 -07:00

109 lines
3.3 KiB
Nix

# @NOTE(jakehamilton): The role of this file is to bootstrap the
# Snowfall library. There is some duplication shared between this
# file and the library itself due to the library needing to pass through
# another extended library for its own applications.
core-inputs:
user-options:
let
user-inputs = user-options.inputs // { src = user-options.src; };
inherit (core-inputs.nixpkgs.lib) assertMsg fix filterAttrs mergeAttrs fold recursiveUpdate;
# Recursively merge a list of attribute sets.
# Type: [Attrs] -> Attrs
# Usage: merge-deep [{ x = 1; } { x = 2; }]
# result: { x = 2; }
merge-deep = fold recursiveUpdate { };
# Merge the root of a list of attribute sets.
# Type: [Attrs] -> Attrs
# Usage: merge-shallow [{ x = 1; } { x = 2; }]
# result: { x = 2; }
merge-shallow = fold mergeAttrs { };
# Transform an attribute set of inputs into an attribute set where
# the values are the inputs' `lib` attribute. Entries without a `lib`
# attribute are removed.
# Type: Attrs -> Attrs
# Usage: get-lib { x = nixpkgs; y = {}; }
# result: { x = nixpkgs.lib; }
get-libs = attrs:
let
# @PERF(jakehamilton): Replace filter+map with a fold.
attrs-with-libs = filterAttrs
(name: value: builtins.isAttrs (value.lib or null))
attrs;
libs =
builtins.mapAttrs (name: input: input.lib) attrs-with-libs;
in
libs;
# Remove the `self` attribute from an attribute set.
# Type: Attrs -> Attrs
# Usage: without-self { self = {}; x = true; }
# result: { x = true; }
without-self = attrs: builtins.removeAttrs attrs [ "self" ];
core-inputs-libs = get-libs (without-self core-inputs);
user-inputs-libs = get-libs (without-self user-inputs);
snowfall-lib-root = "${core-inputs.src}/lib";
snowfall-lib-dirs =
let
files = builtins.readDir snowfall-lib-root;
dirs = filterAttrs (name: kind: kind == "directory") files;
names = builtins.attrNames dirs;
in
names;
snowfall-lib = fix (snowfall-lib:
let
attrs = {
inherit snowfall-lib core-inputs user-inputs;
};
libs = builtins.map
(dir: import "${snowfall-lib-root}/${dir}" attrs)
snowfall-lib-dirs;
in
merge-deep libs
);
snowfall-top-level-lib = filterAttrs (name: value: !builtins.isAttrs value) snowfall-lib;
base-lib = merge-shallow [
core-inputs.nixpkgs.lib
core-inputs-libs
user-inputs-libs
snowfall-top-level-lib
{ snowfall = snowfall-lib; }
];
user-lib-root = "${user-inputs.src}/lib";
user-lib-modules = snowfall-lib.fs.get-default-nix-files-recursive user-lib-root;
user-lib = fix (user-lib:
let
attrs = {
inherit (user-options) inputs;
snowfall-inputs = core-inputs;
lib = merge-shallow [ base-lib user-lib ];
};
libs = builtins.map
(path: import path attrs)
user-lib-modules;
in
merge-deep libs
);
lib = merge-deep [
base-lib
user-lib
];
user-inputs-has-self = builtins.elem "self" (builtins.attrNames user-inputs);
user-inputs-has-src = builtins.elem "src" (builtins.attrNames user-inputs);
in
assert (assertMsg (user-inputs-has-self) "Missing attribute `self` for mkLib.");
assert (assertMsg (user-inputs-has-src) "Missing attribute `src` for mkLib.");
lib