lib/trivial: unify & improve docstrings

- add section headers
- unify comment syntax
- add examples

Tested with:
nix-instantiate --strict --eval ./lib/tests/misc.nix
This commit is contained in:
Profpatsch 2018-07-26 00:03:51 +02:00
parent bbe31da148
commit af10842940
1 changed files with 61 additions and 23 deletions

View File

@ -38,6 +38,8 @@ let
in
rec {
## Simple (higher order) functions
/* The identity function
For when you need a function that does nothing.
@ -59,7 +61,7 @@ rec {
## Named versions corresponding to some builtin operators.
/* Concat two strings */
/* Concatenate two lists */
concat = x: y: x ++ y;
/* boolean or */
@ -93,10 +95,22 @@ rec {
*/
mergeAttrs = x: y: x // y;
# Flip the order of the arguments of a binary function.
/* Flip the order of the arguments of a binary function.
Example:
flip concat [1] [2]
=> [ 2 1 ]
*/
flip = f: a: b: f b a;
# Apply function if argument is non-null
/* Apply function if argument is non-null.
Example:
mapNullable (x: x+1) null
=> null
mapNullable (x: x+1) 22
=> 23
*/
mapNullable = f: a: if isNull a then a else f a;
# Pull in some builtins not included elsewhere.
@ -105,20 +119,30 @@ rec {
isInt isFloat add sub lessThan
seq deepSeq genericClosure;
inherit (lib.strings) fileContents;
release = fileContents ../.version;
versionSuffix = let suffixFile = ../.version-suffix; in
if pathExists suffixFile then fileContents suffixFile else "pre-git";
## nixpks version strings
# Return the Nixpkgs version number.
# The current full nixpkgs version number.
version = release + versionSuffix;
# The current nixpkgs version number as string.
release = lib.strings.fileContents ../.version;
# The current nixpkgs version suffix as string.
versionSuffix =
let suffixFile = ../.version-suffix;
in if pathExists suffixFile
then lib.strings.fileContents suffixFile
else "pre-git";
nixpkgsVersion = builtins.trace "`lib.nixpkgsVersion` is deprecated, use `lib.version` instead!" version;
# Whether we're being called by nix-shell.
inNixShell = builtins.getEnv "IN_NIX_SHELL" != "";
## Integer operations
# Return minimum/maximum of two numbers.
min = x: y: if x < y then x else y;
max = x: y: if x > y then x else y;
@ -133,6 +157,9 @@ rec {
*/
mod = base: int: base - (int * (builtins.div base int));
## Comparisons
/* C-style comparisons
a < b, compare a b => -1
@ -162,17 +189,20 @@ rec {
cmp "fooa" "a" => -1
# while
compare "fooa" "a" => 1
*/
splitByAndCompare = p: yes: no: a: b:
if p a
then if p b then yes a b else -1
else if p b then 1 else no a b;
/* Reads a JSON file. */
importJSON = path:
builtins.fromJSON (builtins.readFile path);
## Warnings and asserts
/* See https://github.com/NixOS/nix/issues/749. Eventually we'd like these
to expand to Nix builtins that carry metadata so that Nix can filter out
the INFO messages without parsing the message string.
@ -188,28 +218,36 @@ rec {
warn = msg: builtins.trace "WARNING: ${msg}";
info = msg: builtins.trace "INFO: ${msg}";
# | Add metadata about expected function arguments to a function.
# The metadata should match the format given by
# builtins.functionArgs, i.e. a set from expected argument to a bool
# representing whether that argument has a default or not.
# setFunctionArgs : (a → b) → Map String Bool → (a → b)
#
# This function is necessary because you can't dynamically create a
# function of the { a, b ? foo, ... }: format, but some facilities
# like callPackage expect to be able to query expected arguments.
## Function annotations
/* Add metadata about expected function arguments to a function.
The metadata should match the format given by
builtins.functionArgs, i.e. a set from expected argument to a bool
representing whether that argument has a default or not.
setFunctionArgs : (a b) Map String Bool (a b)
This function is necessary because you can't dynamically create a
function of the { a, b ? foo, ... }: format, but some facilities
like callPackage expect to be able to query expected arguments.
*/
setFunctionArgs = f: args:
{ # TODO: Should we add call-time "type" checking like built in?
__functor = self: f;
__functionArgs = args;
};
# | Extract the expected function arguments from a function.
# This works both with nix-native { a, b ? foo, ... }: style
# functions and functions with args set with 'setFunctionArgs'. It
# has the same return type and semantics as builtins.functionArgs.
# setFunctionArgs : (a → b) → Map String Bool.
/* Extract the expected function arguments from a function.
This works both with nix-native { a, b ? foo, ... }: style
functions and functions with args set with 'setFunctionArgs'. It
has the same return type and semantics as builtins.functionArgs.
setFunctionArgs : (a b) Map String Bool.
*/
functionArgs = f: f.__functionArgs or (builtins.functionArgs f);
/* Check whether something is a function or something
annotated with function args.
*/
isFunction = f: builtins.isFunction f ||
(f ? __functor && isFunction (f.__functor f));
}