From af108429408b1b220fab4048ff44d674f52fdee6 Mon Sep 17 00:00:00 2001 From: Profpatsch Date: Thu, 26 Jul 2018 00:03:51 +0200 Subject: [PATCH] lib/trivial: unify & improve docstrings - add section headers - unify comment syntax - add examples Tested with: nix-instantiate --strict --eval ./lib/tests/misc.nix --- lib/trivial.nix | 84 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 61 insertions(+), 23 deletions(-) diff --git a/lib/trivial.nix b/lib/trivial.nix index fac0718a9e7..a36056253d7 100644 --- a/lib/trivial.nix +++ b/lib/trivial.nix @@ -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)); }