-
-
Notifications
You must be signed in to change notification settings - Fork 14.1k
/
trivial.nix
335 lines (258 loc) · 8.61 KB
/
trivial.nix
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
{ lib }:
rec {
## Simple (higher order) functions
/* The identity function
For when you need a function that does “nothing”.
Type: id :: a -> a
*/
id =
# The value to return
x: x;
/* The constant function
Ignores the second argument. If called with only one argument,
constructs a function that always returns a static value.
Type: const :: a -> b -> a
Example:
let f = const 5; in f 10
=> 5
*/
const =
# Value to return
x:
# Value to ignore
y: x;
/* Pipes a value through a list of functions, left to right.
Type: pipe :: a -> [<functions>] -> <return type of last function>
Example:
pipe 2 [
(x: x + 2) # 2 + 2 = 4
(x: x * 2) # 4 * 2 = 8
]
=> 8
# ideal to do text transformations
pipe [ "a/b" "a/c" ] [
# create the cp command
(map (file: ''cp "${src}/${file}" $out\n''))
# concatenate all commands into one string
lib.concatStrings
# make that string into a nix derivation
(pkgs.runCommand "copy-to-out" {})
]
=> <drv which copies all files to $out>
The output type of each function has to be the input type
of the next function, and the last function returns the
final value.
*/
pipe = val: functions:
let reverseApply = x: f: f x;
in builtins.foldl' reverseApply val functions;
/* note please don’t add a function like `compose = flip pipe`.
This would confuse users, because the order of the functions
in the list is not clear. With pipe, it’s obvious that it
goes first-to-last. With `compose`, not so much.
*/
## Named versions corresponding to some builtin operators.
/* Concatenate two lists
Type: concat :: [a] -> [a] -> [a]
Example:
concat [ 1 2 ] [ 3 4 ]
=> [ 1 2 3 4 ]
*/
concat = x: y: x ++ y;
/* boolean “or” */
or = x: y: x || y;
/* boolean “and” */
and = x: y: x && y;
/* bitwise “and” */
bitAnd = builtins.bitAnd
or (import ./zip-int-bits.nix
(a: b: if a==1 && b==1 then 1 else 0));
/* bitwise “or” */
bitOr = builtins.bitOr
or (import ./zip-int-bits.nix
(a: b: if a==1 || b==1 then 1 else 0));
/* bitwise “xor” */
bitXor = builtins.bitXor
or (import ./zip-int-bits.nix
(a: b: if a!=b then 1 else 0));
/* bitwise “not” */
bitNot = builtins.sub (-1);
/* Convert a boolean to a string.
This function uses the strings "true" and "false" to represent
boolean values. Calling `toString` on a bool instead returns "1"
and "" (sic!).
Type: boolToString :: bool -> string
*/
boolToString = b: if b then "true" else "false";
/* Merge two attribute sets shallowly, right side trumps left
mergeAttrs :: attrs -> attrs -> attrs
Example:
mergeAttrs { a = 1; b = 2; } { b = 3; c = 4; }
=> { a = 1; b = 3; c = 4; }
*/
mergeAttrs =
# Left attribute set
x:
# Right attribute set (higher precedence for equal keys)
y: x // y;
/* Flip the order of the arguments of a binary function.
Type: flip :: (a -> b -> c) -> (b -> a -> c)
Example:
flip concat [1] [2]
=> [ 2 1 ]
*/
flip = f: a: b: f b a;
/* Apply function if the supplied argument is non-null.
Example:
mapNullable (x: x+1) null
=> null
mapNullable (x: x+1) 22
=> 23
*/
mapNullable =
# Function to call
f:
# Argument to check for null before passing it to `f`
a: if a == null then a else f a;
# Pull in some builtins not included elsewhere.
inherit (builtins)
pathExists readFile isBool
isInt isFloat add sub lessThan
seq deepSeq genericClosure;
## nixpks version strings
/* Returns the current full nixpkgs version number. */
version = release + versionSuffix;
/* Returns the current nixpkgs release number as string. */
release = lib.strings.fileContents ../.version;
/* Returns the current nixpkgs release code name.
On each release the first letter is bumped and a new animal is chosen
starting with that new letter.
*/
codeName = "Nightingale";
/* Returns the current nixpkgs version suffix as string. */
versionSuffix =
let suffixFile = ../.version-suffix;
in if pathExists suffixFile
then lib.strings.fileContents suffixFile
else "pre-git";
/* Attempts to return the the current revision of nixpkgs and
returns the supplied default value otherwise.
Type: revisionWithDefault :: string -> string
*/
revisionWithDefault =
# Default value to return if revision can not be determined
default:
let
revisionFile = "${toString ./..}/.git-revision";
gitRepo = "${toString ./..}/.git";
in if lib.pathIsGitRepo gitRepo
then lib.commitIdFromGitRepo gitRepo
else if lib.pathExists revisionFile then lib.fileContents revisionFile
else default;
nixpkgsVersion = builtins.trace "`lib.nixpkgsVersion` is deprecated, use `lib.version` instead!" version;
/* Determine whether the function is being called from inside a Nix
shell.
Type: inNixShell :: bool
*/
inNixShell = builtins.getEnv "IN_NIX_SHELL" != "";
## Integer operations
/* Return minimum of two numbers. */
min = x: y: if x < y then x else y;
/* Return maximum of two numbers. */
max = x: y: if x > y then x else y;
/* Integer modulus
Example:
mod 11 10
=> 1
mod 1 10
=> 1
*/
mod = base: int: base - (int * (builtins.div base int));
## Comparisons
/* C-style comparisons
a < b, compare a b => -1
a == b, compare a b => 0
a > b, compare a b => 1
*/
compare = a: b:
if a < b
then -1
else if a > b
then 1
else 0;
/* Split type into two subtypes by predicate `p`, take all elements
of the first subtype to be less than all the elements of the
second subtype, compare elements of a single subtype with `yes`
and `no` respectively.
Type: (a -> bool) -> (a -> a -> int) -> (a -> a -> int) -> (a -> a -> int)
Example:
let cmp = splitByAndCompare (hasPrefix "foo") compare compare; in
cmp "a" "z" => -1
cmp "fooa" "fooz" => -1
cmp "f" "a" => 1
cmp "fooa" "a" => -1
# while
compare "fooa" "a" => 1
*/
splitByAndCompare =
# Predicate
p:
# Comparison function if predicate holds for both values
yes:
# Comparison function if predicate holds for neither value
no:
# First value to compare
a:
# Second value to compare
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.
Type :: path -> any
*/
importJSON = path:
builtins.fromJSON (builtins.readFile path);
## Warnings
# 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.
#
# Usage:
# {
# foo = lib.warn "foo is deprecated" oldFoo;
# }
#
# TODO: figure out a clever way to integrate location information from
# something like __unsafeGetAttrPos.
warn = msg: builtins.trace "[1;31mwarning: ${msg}[0m";
info = msg: builtins.trace "INFO: ${msg}";
showWarnings = warnings: res: lib.fold (w: x: warn w x) res warnings;
## 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.
*/
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));
}