aboutsummaryrefslogtreecommitdiff
path: root/guix/derivations.scm
blob: d5e0f453e25650eeca7f6154d336ee6bdbc10bcf (plain)
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
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016, 2017 Mathieu Lirzin <mthl@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (guix derivations)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-9 gnu)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (ice-9 binary-ports)
  #:use-module (rnrs bytevectors)
  #:use-module (ice-9 match)
  #:use-module (ice-9 rdelim)
  #:use-module (ice-9 vlist)
  #:use-module (guix store)
  #:use-module (guix utils)
  #:use-module (guix base16)
  #:use-module (guix memoization)
  #:use-module (guix combinators)
  #:use-module (guix monads)
  #:use-module (guix hash)
  #:use-module (guix base32)
  #:use-module (guix records)
  #:use-module (guix sets)
  #:export (<derivation>
            derivation?
            derivation-outputs
            derivation-inputs
            derivation-sources
            derivation-system
            derivation-builder
            derivation-builder-arguments
            derivation-builder-environment-vars
            derivation-file-name
            derivation-prerequisites
            derivation-prerequisites-to-build

            <derivation-output>
            derivation-output?
            derivation-output-path
            derivation-output-hash-algo
            derivation-output-hash
            derivation-output-recursive?

            <derivation-input>
            derivation-input?
            derivation-input-path
            derivation-input-sub-derivations
            derivation-input-output-paths
            valid-derivation-input?

            &derivation-error
            derivation-error?
            derivation-error-derivation
            &derivation-missing-output-error
            derivation-missing-output-error?
            derivation-missing-output

            derivation-name
            derivation-output-names
            fixed-output-derivation?
            fixed-output-path
            offloadable-derivation?
            substitutable-derivation?
            substitution-oracle
            derivation-hash

            read-derivation
            write-derivation
            derivation->output-path
            derivation->output-paths
            derivation-path->output-path
            derivation-path->output-paths
            derivation
            raw-derivation

            map-derivation

            build-derivations
            built-derivations

            file-search-error?
            file-search-error-file-name
            file-search-error-search-path

            search-path*
            module->source-file-name
            build-expression->derivation)

  ;; Re-export it from here for backward compatibility.
  #:re-export (%guile-for-build))

;;;
;;; Error conditions.
;;;

(define-condition-type &derivation-error &nix-error
  derivation-error?
  (derivation derivation-error-derivation))

(define-condition-type &derivation-missing-output-error &derivation-error
  derivation-missing-output-error?
  (output derivation-missing-output))

;;;
;;; Nix derivations, as implemented in Nix's `derivations.cc'.
;;;

(define-immutable-record-type <derivation>
  (make-derivation outputs inputs sources system builder args env-vars
                   file-name)
  derivation?
  (outputs  derivation-outputs)      ; list of name/<derivation-output> pairs
  (inputs   derivation-inputs)       ; list of <derivation-input>
  (sources  derivation-sources)      ; list of store paths
  (system   derivation-system)       ; string
  (builder  derivation-builder)      ; store path
  (args     derivation-builder-arguments)         ; list of strings
  (env-vars derivation-builder-environment-vars)  ; list of name/value pairs
  (file-name derivation-file-name))               ; the .drv file name

(define-record-type <derivation-output>
  (make-derivation-output path hash-algo hash recursive?)
  derivation-output?
  (path       derivation-output-path)             ; store path
  (hash-algo  derivation-output-hash-algo)        ; symbol | #f
  (hash       derivation-output-hash)             ; bytevector | #f
  (recursive? derivation-output-recursive?))      ; Boolean

(define-record-type <derivation-input>
  (make-derivation-input path sub-derivations)
  derivation-input?
  (path            derivation-input-path)             ; store path
  (sub-derivations derivation-input-sub-derivations)) ; list of strings

(set-record-type-printer! <derivation>
                          (lambda (drv port)
                            (format port "#<derivation ~a => ~a ~a>"
                                    (derivation-file-name drv)
                                    (string-join
                                     (map (match-lambda
                                           ((_ . output)
                                            (derivation-output-path output)))
                                          (derivation-outputs drv)))
                                    (number->string (object-address drv) 16))))

(define (derivation-name drv)
  "Return the base name of DRV."
  (let ((base (store-path-package-name (derivation-file-name drv))))
    (string-drop-right base 4)))

(define (derivation-output-names drv)
  "Return the names of the outputs of DRV."
  (match (derivation-outputs drv)
    (((names . _) ...)
     names)))

(define (fixed-output-derivation? drv)
  "Return #t if DRV is a fixed-output derivation, such as the result of a
download with a fixed hash (aka. `fetchurl')."
  (match drv
    (($ <derivation>
        (("out" . ($ <derivation-output> _ (? symbol?) (? bytevector?)))))
     #t)
    (_ #f)))

(define (derivation-input<? input1 input2)
  "Compare INPUT1 and INPUT2, two <derivation-input>."
  (string<? (derivation-input-path input1)
            (derivation-input-path input2)))

(define (derivation-input-output-paths input)
  "Return the list of output paths corresponding to INPUT, a
<derivation-input>."
  (match input
    (($ <derivation-input> path sub-drvs)
     (map (cut derivation-path->output-path path <>)
          sub-drvs))))

(define (valid-derivation-input? store input)
  "Return true if INPUT is valid--i.e., if all the outputs it requests are in
the store."
  (every (cut valid-path? store <>)
         (derivation-input-output-paths input)))

(define (coalesce-duplicate-inputs inputs)
  "Return a list of inputs, such that when INPUTS contains the same DRV twice,
they are coalesced, with their sub-derivations merged.  This is needed because
Nix itself keeps only one of them."
  (fold (lambda (input result)
          (match input
            (($ <derivation-input> path sub-drvs)
             ;; XXX: quadratic
             (match (find (match-lambda
                            (($ <derivation-input> p s)
                             (string=? p path)))
                          result)
               (#f
                (cons input result))
               ((and dup ($ <derivation-input> _ sub-drvs2))
                ;; Merge DUP with INPUT.
                (let ((sub-drvs (delete-duplicates
                                 (append sub-drvs sub-drvs2))))
                  (cons (make-derivation-input path
                                               (sort sub-drvs string<?))
                        (delq dup result))))))))
        '()
        inputs))

(define* (derivation-prerequisites drv #:optional (cut? (const #f)))
  "Return the list of derivation-inputs required to build DRV, recursively.

CUT? is a predicate that is passed a derivation-input and returns true to
eliminate the given input and its dependencies from the search.  An example of
search a predicate is 'valid-derivation-input?'; when it is used as CUT?, the
result is the set of prerequisites of DRV not already in valid."
  (let loop ((drv       drv)
             (result    '())
             (input-set (set)))
    (let ((inputs (remove (lambda (input)
                            (or (set-contains? input-set input)
                                (cut? input)))
                          (derivation-inputs drv))))
      (fold2 loop
             (append inputs result)
             (fold set-insert input-set inputs)
             (map (lambda (i)
                    (call-with-input-file (derivation-input-path i)
                      read-derivation))
                  inputs)))))

(define (offloadable-derivation? drv)
  "Return true if DRV can be offloaded, false otherwise."
  (match (assoc "preferLocalBuild"
                (derivation-builder-environment-vars drv))
    (("preferLocalBuild" . "1") #f)
    (_ #t)))

(define (substitutable-derivation? drv)
  "Return #t if DRV can be substituted."
  (match (assoc "allowSubstitutes"
                (derivation-builder-environment-vars drv))
    (("allowSubstitutes" . value)
     (string=? value "1"))
    (_ #t)))

(define (derivation-output-paths drv sub-drvs)
  "Return the output paths of outputs SUB-DRVS of DRV."
  (match drv
    (($ <derivation> outputs)
     (map (lambda (sub-drv)
            (derivation-output-path (assoc-ref outputs sub-drv)))
          sub-drvs))))

(define* (substitution-oracle store drv
                              #:key (mode (build-mode normal)))
  "Return a one-argument procedure that, when passed a store file name,
returns #t if it's substitutable and #f otherwise.  The returned procedure
knows about all substitutes for all the derivations listed in DRV, *except*
those that are already valid (that is, it won't bother checking whether an
item is substitutable if it's already on disk); it also knows about their
prerequisites, unless they are themselves substitutable.

Creating a single oracle (thus making a single 'substitutable-paths' call) and
reusing it is much more efficient than calling 'has-substitutes?' or similar
repeatedly, because it avoids the costs associated with launching the
substituter many times."
  (define valid?
    (cut valid-path? store <>))

  (define valid-input?
    (cut valid-derivation-input? store <>))

  (define (dependencies drv)
    ;; Skip prerequisite sub-trees of DRV whose root is valid.  This allows us
    ;; to ask the substituter for just as much as needed, instead of asking it
    ;; for the whole world, which can be significantly faster when substitute
    ;; info is not already in cache.
    ;; Also, skip derivations marked as non-substitutable.
    (append-map (lambda (input)
                  (let ((drv (call-with-input-file
                                 (derivation-input-path input)
                               read-derivation)))
                    (if (substitutable-derivation? drv)
                        (derivation-input-output-paths input)
                        '())))
                (derivation-prerequisites drv valid-input?)))

  (let* ((paths (delete-duplicates
                 (concatenate
                  (fold (lambda (drv result)
                          (let ((self (match (derivation->output-paths drv)
                                        (((names . paths) ...)
                                         paths))))
                            (cond ((eqv? mode (build-mode check))
                                   (cons (dependencies drv) result))
                                  ((not (substitutable-derivation? drv))
                                   (cons (dependencies drv) result))
                                  ((every valid? self)
                                   result)
                                  (else
                                   (cons* self (dependencies drv) result)))))
                        '()
                        drv))))
         (subst (list->set (substitutable-paths store paths))))
    (cut set-contains? subst <>)))

(define* (derivation-prerequisites-to-build store drv
                                            #:key
                                            (mode (build-mode normal))
                                            (outputs
                                             (derivation-output-names drv))
                                            (substitutable?
                                             (substitution-oracle store
                                                                  (list drv)
                                                                  #:mode mode)))
  "Return two values: the list of derivation-inputs required to build the
OUTPUTS of DRV and not already available in STORE, recursively, and the list
of required store paths that can be substituted.  SUBSTITUTABLE? must be a
one-argument procedure similar to that returned by 'substitution-oracle'."
  (define built?
    (cut valid-path? store <>))

  (define input-built?
    (compose (cut any built? <>) derivation-input-output-paths))

  (define input-substitutable?
    ;; Return true if and only if all of SUB-DRVS are subsitutable.  If at
    ;; least one is missing, then everything must be rebuilt.
    (compose (cut every substitutable? <>) derivation-input-output-paths))

  (define (derivation-built? drv* sub-drvs)
    ;; In 'check' mode, assume that DRV is not built.
    (and (not (and (eqv? mode (build-mode check))
                   (eq? drv* drv)))
         (every built? (derivation-output-paths drv* sub-drvs))))

  (define (derivation-substitutable? drv sub-drvs)
    (and (substitutable-derivation? drv)
         (every substitutable? (derivation-output-paths drv sub-drvs))))

  (let loop ((drv        drv)
             (sub-drvs   outputs)
             (build      '())
             (substitute '()))
    (cond ((derivation-built? drv sub-drvs)
           (values build substitute))
          ((derivation-substitutable? drv sub-drvs)
           (values build
                   (append (derivation-output-paths drv sub-drvs)
                           substitute)))
          (else
           (let ((build  (if (substitutable-derivation? drv)
                             build
                             (cons (make-derivation-input
                                    (derivation-file-name drv) sub-drvs)
                                   build)))
                 (inputs (remove (lambda (i)
                                   (or (member i build) ; XXX: quadratic
                                       (input-built? i)
                                       (input-substitutable? i)))
                                 (derivation-inputs drv))))
             (fold2 loop
                    (append inputs build)
                    (append (append-map (lambda (input)
                                          (if (and (not (input-built? input))
                                                   (input-substitutable? input))
                                              (derivation-input-output-paths
                                               input)
                                              '()))
                                        (derivation-inputs drv))
                            substitute)
                    (map (lambda (i)
                           (call-with-input-file (derivation-input-path i)
                             read-derivation))
                         inputs)
                    (map derivation-input-sub-derivations inputs)))))))

(define (%read-derivation drv-port)
  ;; Actually read derivation from DRV-PORT.

  (define comma (string->symbol ","))

  (define (ununquote x)
    (match x
      (('unquote x) (ununquote x))
      ((x ...)      (map ununquote x))
      (_            x)))

  (define (outputs->alist x)
    (fold-right (lambda (output result)
                  (match output
                    ((name path "" "")
                     (alist-cons name
                                 (make-derivation-output path #f #f #f)
                                 result))
                    ((name path hash-algo hash)
                     ;; fixed-output
                     (let* ((rec? (string-prefix? "r:" hash-algo))
                            (algo (string->symbol
                                   (if rec?
                                       (string-drop hash-algo 2)
                                       hash-algo)))
                            (hash (base16-string->bytevector hash)))
                       (alist-cons name
                                   (make-derivation-output path algo
                                                           hash rec?)
                                   result)))))
                '()
                x))

  (define (make-input-drvs x)
    (fold-right (lambda (input result)
                  (match input
                    ((path (sub-drvs ...))
                     (cons (make-derivation-input path sub-drvs)
                           result))))
                '()
                x))

  ;; The contents of a derivation are typically ASCII, but choosing
  ;; UTF-8 allows us to take the fast path for Guile's `scm_getc'.
  (set-port-encoding! drv-port "UTF-8")

  (let loop ((exp    (read drv-port))
             (result '()))
    (match exp
      ((? eof-object?)
       (let ((result (reverse result)))
         (match result
           (('Derive ((outputs ...) (input-drvs ...)
                      (input-srcs ...)
                      (? string? system)
                      (? string? builder)
                      ((? string? args) ...)
                      ((var value) ...)))
            (make-derivation (outputs->alist outputs)
                             (make-input-drvs input-drvs)
                             input-srcs
                             system builder args
                             (fold-right alist-cons '() var value)
                             (port-filename drv-port)))
           (_
            (error "failed to parse derivation" drv-port result)))))
      ((? (cut eq? <> comma))
       (loop (read drv-port) result))
      (_
       (loop (read drv-port)
             (cons (ununquote exp) result))))))

(define %derivation-cache
  ;; Maps derivation file names to <derivation> objects.
  ;; XXX: This is redundant with 'atts-cache' in the store.
  (make-weak-value-hash-table 200))

(define (read-derivation drv-port)
  "Read the derivation from DRV-PORT and return the corresponding
<derivation> object."
  ;; Memoize that operation because `%read-derivation' is quite expensive,
  ;; and because the same argument is read more than 15 times on average
  ;; during something like (package-derivation s gdb).
  (let ((file (port-filename drv-port)))
    (or (and file (hash-ref %derivation-cache file))
        (let ((drv (%read-derivation drv-port)))
          (hash-set! %derivation-cache file drv)
          drv))))

(define-inlinable (write-sequence lst write-item port)
  ;; Write each element of LST with WRITE-ITEM to PORT, separating them with a
  ;; comma.
  (match lst
    (()
     #t)
    ((prefix (... ...) last)
     (for-each (lambda (item)
                 (write-item item port)
                 (display "," port))
               prefix)
     (write-item last port))))

(define-inlinable (write-list lst write-item port)
  ;; Write LST as a derivation list to PORT, using WRITE-ITEM to write each
  ;; element.
  (display "[" port)
  (write-sequence lst write-item port)
  (display "]" port))

(define-inlinable (write-tuple lst write-item port)
  ;; Same, but write LST as a tuple.
  (display "(" port)
  (write-sequence lst write-item port)
  (display ")" port))

(define (write-derivation drv port)
  "Write the ATerm-like serialization of DRV to PORT.  See Section 2.4 of
Eelco Dolstra's PhD dissertation for an overview of a previous version of
that form."

  ;; Make sure we're using the faster implementation.
  (define format simple-format)

  (define (write-string-list lst)
    (write-list lst write port))

  (define (write-output output port)
    (match output
     ((name . ($ <derivation-output> path hash-algo hash recursive?))
      (write-tuple (list name path
                         (if hash-algo
                             (string-append (if recursive? "r:" "")
                                            (symbol->string hash-algo))
                             "")
                         (or (and=> hash bytevector->base16-string)
                             ""))
                   write
                   port))))

  (define (write-input input port)
    (match input
      (($ <derivation-input> path sub-drvs)
       (display "(\"" port)
       (display path port)
       (display "\"," port)
       (write-string-list sub-drvs)
       (display ")" port))))

  (define (write-env-var env-var port)
    (match env-var
      ((name . value)
       (display "(" port)
       (write name port)
       (display "," port)
       (write value port)
       (display ")" port))))

  ;; Assume all the lists we are writing are already sorted.
  (match drv
    (($ <derivation> outputs inputs sources
        system builder args env-vars)
     (display "Derive(" port)
     (write-list outputs write-output port)
     (display "," port)
     (write-list inputs write-input port)
     (display "," port)
     (write-string-list sources)
     (simple-format port ",\"~a\",\"~a\"," system builder)
     (write-string-list args)
     (display "," port)
     (write-list env-vars write-env-var port)
     (display ")" port))))

(define derivation->bytevector
  (mlambda (drv)
    "Return the external representation of DRV as a UTF-8-encoded string."
    (with-fluids ((%default-port-encoding "UTF-8"))
      (call-with-values open-bytevector-output-port
        (lambda (port get-bytevector)
          (write-derivation drv port)
          (get-bytevector))))))

(define* (derivation->output-path drv #:optional (output "out"))
  "Return the store path of its output OUTPUT.  Raise a
'&derivation-missing-output-error' condition if OUTPUT is not an output of
DRV."
  (let ((output* (assoc-ref (derivation-outputs drv) output)))
    (if output*
        (derivation-output-path output*)
        (raise (condition (&derivation-missing-output-error
                           (derivation drv)
                           (output output)))))))

(define (derivation->output-paths drv)
  "Return the list of name/path pairs of the outputs of DRV."
  (map (match-lambda
        ((name . output)
         (cons name (derivation-output-path output))))
       (derivation-outputs drv)))

(define derivation-path->output-path
  ;; This procedure is called frequently, so memoize it.
  (let ((memoized (mlambda (path output)
                    (derivation->output-path (call-with-input-file path
                                               read-derivation)
                                             output))))
    (lambda* (path #:optional (output "out"))
      "Read the derivation from PATH (`/gnu/store/xxx.drv'), and return the store
path of its output OUTPUT."
      (memoized path output))))

(define (derivation-path->output-paths path)
  "Read the derivation from PATH (`/gnu/store/xxx.drv'), and return the
list of name/path pairs of its outputs."
  (derivation->output-paths (call-with-input-file path read-derivation)))


;;;
;;; Derivation primitive.
;;;

(define (compressed-hash bv size)                 ; `compressHash'
  "Given the hash stored in BV, return a compressed version thereof that fits
in SIZE bytes."
  (define new (make-bytevector size 0))
  (define old-size (bytevector-length bv))
  (let loop ((i 0))
    (if (= i old-size)
        new
        (let* ((j (modulo i size))
               (o (bytevector-u8-ref new j)))
          (bytevector-u8-set! new j
                              (logxor o (bytevector-u8-ref bv i)))
          (loop (+ 1 i))))))

(define derivation-path->base16-hash
  (mlambda (file)
    "Return a string containing the base16 representation of the hash of the
derivation at FILE."
    (call-with-input-file file
      (compose bytevector->base16-string
               derivation-hash
               read-derivation))))

(define derivation-hash            ; `hashDerivationModulo' in derivations.cc
  (mlambda (drv)
    "Return the hash of DRV, modulo its fixed-output inputs, as a bytevector."
    (match drv
      (($ <derivation> ((_ . ($ <derivation-output> path
                                                    (? symbol? hash-algo) (? bytevector? hash)
                                                    (? boolean? recursive?)))))
       ;; A fixed-output derivation.
       (sha256
        (string->utf8
         (string-append "fixed:out:"
                        (if recursive? "r:" "")
                        (symbol->string hash-algo)
                        ":" (bytevector->base16-string hash)
                        ":" path))))
      (($ <derivation> outputs inputs sources
                       system builder args env-vars)
       ;; A regular derivation: replace the path of each input with that
       ;; input's hash; return the hash of serialization of the resulting
       ;; derivation.
       (let* ((inputs (map (match-lambda
                             (($ <derivation-input> path sub-drvs)
                              (let ((hash (derivation-path->base16-hash path)))
                                (make-derivation-input hash sub-drvs))))
                           inputs))
              (drv    (make-derivation outputs
                                       (sort (coalesce-duplicate-inputs inputs)
                                             derivation-input<?)
                                       sources
                                       system builder args env-vars
                                       #f)))

         ;; XXX: At this point this remains faster than `port-sha256', because
         ;; the SHA256 port's `write' method gets called for every single
         ;; character.
         (sha256 (derivation->bytevector drv)))))))

(define (store-path type hash name)               ; makeStorePath
  "Return the store path for NAME/HASH/TYPE."
  (let* ((s (string-append type ":sha256:"
                           (bytevector->base16-string hash) ":"
                           (%store-prefix) ":" name))
         (h (sha256 (string->utf8 s)))
         (c (compressed-hash h 20)))
    (string-append (%store-prefix) "/"
                   (bytevector->nix-base32-string c) "-"
                   name)))

(define (output-path output hash name)            ; makeOutputPath
  "Return an output path for OUTPUT (the name of the output as a string) of
the derivation called NAME with hash HASH."
  (store-path (string-append "output:" output) hash
              (if (string=? output "out")
                  name
                  (string-append name "-" output))))

(define* (fixed-output-path name hash
                            #:key
                            (output "out")
                            (hash-algo 'sha256)
                            (recursive? #t))
  "Return an output path for the fixed output OUTPUT defined by HASH of type
HASH-ALGO, of the derivation NAME.  RECURSIVE? has the same meaning as for
'add-to-store'."
  (if (and recursive? (eq? hash-algo 'sha256))
      (store-path "source" hash name)
      (let ((tag (string-append "fixed:" output ":"
                                (if recursive? "r:" "")
                                (symbol->string hash-algo) ":"
                                (bytevector->base16-string hash) ":")))
        (store-path (string-append "output:" output)
                    (sha256 (string->utf8 tag))
                    name))))

(define* (derivation store name builder args
                     #:key
                     (system (%current-system)) (env-vars '())
                     (inputs '()) (outputs '("out"))
                     hash hash-algo recursive?
                     references-graphs
                     allowed-references disallowed-references
                     leaked-env-vars local-build?
                     (substitutable? #t))
  "Build a derivation with the given arguments, and return the resulting
<derivation> object.  When HASH and HASH-ALGO are given, a
fixed-output derivation is created---i.e., one whose result is known in
advance, such as a file download.  If, in addition, RECURSIVE? is true, then
that fixed output may be an executable file or a directory and HASH must be
the hash of an archive containing this output.

When REFERENCES-GRAPHS is true, it must be a list of file name/store path
pairs.  In that case, the reference graph of each store path is exported in
the build environment in the corresponding file, in a simple text format.

When ALLOWED-REFERENCES is true, it must be a list of store items or outputs
that the derivation's outputs may refer to.  Likewise, DISALLOWED-REFERENCES,
if true, must be a list of things the outputs may not refer to.

When LEAKED-ENV-VARS is true, it must be a list of strings denoting
environment variables that are allowed to \"leak\" from the daemon's
environment to the build environment.  This is only applicable to fixed-output
derivations--i.e., when HASH is true.  The main use is to allow variables such
as \"http_proxy\" to be passed to derivations that download files.

When LOCAL-BUILD? is true, declare that the derivation is not a good candidate
for offloading and should rather be built locally.  This is the case for small
derivations where the costs of data transfers would outweigh the benefits.

When SUBSTITUTABLE? is false, declare that substitutes of the derivation's
output should not be used."
  (define (add-output-paths drv)
    ;; Return DRV with an actual store path for each of its output and the
    ;; corresponding environment variable.
    (match drv
      (($ <derivation> outputs inputs sources
          system builder args env-vars)
       (let* ((drv-hash (derivation-hash drv))
              (outputs  (map (match-lambda
                              ((output-name . ($ <derivation-output>
                                                 _ algo hash rec?))
                               (let ((path
                                      (if hash
                                          (fixed-output-path name hash
                                                             #:hash-algo algo
                                                             #:output output-name
                                                             #:recursive? rec?)
                                          (output-path output-name
                                                       drv-hash name))))
                                 (cons output-name
                                       (make-derivation-output path algo
                                                               hash rec?)))))
                             outputs)))
         (make-derivation outputs inputs sources system builder args
                          (map (match-lambda
                                ((name . value)
                                 (cons name
                                       (or (and=> (assoc-ref outputs name)
                                                  derivation-output-path)
                                           value))))
                               env-vars)
                          #f)))))

  (define (user+system-env-vars)
    ;; Some options are passed to the build daemon via the env. vars of
    ;; derivations (urgh!).  We hide that from our API, but here is the place
    ;; where we kludgify those options.
    (let ((env-vars `(,@(if local-build?
                            `(("preferLocalBuild" . "1"))
                            '())
                      ,@(if (not substitutable?)
                            `(("allowSubstitutes" . "0"))
                            '())
                      ,@(if allowed-references
                            `(("allowedReferences"
                               . ,(string-join allowed-references)))
                            '())
                      ,@(if disallowed-references
                            `(("disallowedReferences"
                               . ,(string-join disallowed-references)))
                            '())
                      ,@(if leaked-env-vars
                            `(("impureEnvVars"
                               . ,(string-join leaked-env-vars)))
                            '())
                      ,@env-vars)))
      (match references-graphs
        (((file . path) ...)
         (let ((value (map (cut string-append <> " " <>)
                           file path)))
           ;; XXX: This all breaks down if an element of FILE or PATH contains
           ;; white space.
           `(("exportReferencesGraph" . ,(string-join value " "))
             ,@env-vars)))
        (#f
         env-vars))))

  (define (env-vars-with-empty-outputs env-vars)
    ;; Return a variant of ENV-VARS where each OUTPUTS is associated with an
    ;; empty string, even outputs that do not appear in ENV-VARS.
    (let ((e (map (match-lambda
                   ((name . val)
                    (if (member name outputs)
                        (cons name "")
                        (cons name val))))
                  env-vars)))
      (fold (lambda (output-name env-vars)
              (if (assoc output-name env-vars)
                  env-vars
                  (append env-vars `((,output-name . "")))))
            e
            outputs)))

  (define input->derivation-input
    (match-lambda
      (((? derivation? drv))
       (make-derivation-input (derivation-file-name drv) '("out")))
      (((? derivation? drv) sub-drvs ...)
       (make-derivation-input (derivation-file-name drv) sub-drvs))
      (((? direct-store-path? input))
       (make-derivation-input input '("out")))
      (((? direct-store-path? input) sub-drvs ...)
       (make-derivation-input input sub-drvs))
      ((input . _)
       (let ((path (add-to-store store (basename input)
                                 #t "sha256" input)))
         (make-derivation-input path '())))))

  ;; Note: lists are sorted alphabetically, to conform with the behavior of
  ;; C++ `std::map' in Nix itself.

  (let* ((outputs    (map (lambda (name)
                            ;; Return outputs with an empty path.
                            (cons name
                                  (make-derivation-output "" hash-algo
                                                          hash recursive?)))
                          (sort outputs string<?)))
         (inputs     (sort (coalesce-duplicate-inputs
                            (map input->derivation-input
                                 (delete-duplicates inputs)))
                           derivation-input<?))
         (env-vars   (sort (env-vars-with-empty-outputs
                            (user+system-env-vars))
                           (lambda (e1 e2)
                             (string<? (car e1) (car e2)))))
         (drv-masked (make-derivation outputs
                                      (filter (compose derivation-path?
                                                       derivation-input-path)
                                              inputs)
                                      (filter-map (lambda (i)
                                                    (let ((p (derivation-input-path i)))
                                                      (and (not (derivation-path? p))
                                                           p)))
                                                  inputs)
                                      system builder args env-vars #f))
         (drv        (add-output-paths drv-masked)))

    (let* ((file (add-data-to-store store (string-append name ".drv")
                                    (derivation->bytevector drv)
                                    (map derivation-input-path inputs)))
           (drv* (set-field drv (derivation-file-name) file)))
      (hash-set! %derivation-cache file drv*)
      drv*)))

(define* (map-derivation store drv mapping
                         #:key (system (%current-system)))
  "Given MAPPING, a list of pairs of derivations, return a derivation based on
DRV where all the 'car's of MAPPING have been replaced by its 'cdr's,
recursively."
  (define (substitute str initial replacements)
    (fold (lambda (path replacement result)
            (string-replace-substring result path
                                      replacement))
          str
          initial replacements))

  (define (substitute-file file initial replacements)
    (define contents
      (with-fluids ((%default-port-encoding #f))
        (call-with-input-file file read-string)))

    (let ((updated (substitute contents initial replacements)))
      (if (string=? updated contents)
          file
          ;; XXX: permissions aren't preserved.
          (add-text-to-store store (store-path-package-name file)
                             updated))))

  (define input->output-paths
    (match-lambda
     (((? derivation? drv))
      (list (derivation->output-path drv)))
     (((? derivation? drv) sub-drvs ...)
      (map (cut derivation->output-path drv <>)
           sub-drvs))
     ((file)
      (list file))))

  (let ((mapping (fold (lambda (pair result)
                         (match pair
                           (((? derivation? orig) . replacement)
                            (vhash-cons (derivation-file-name orig)
                                        replacement result))
                           ((file . replacement)
                            (vhash-cons file replacement result))))
                       vlist-null
                       mapping)))
    (define rewritten-input
      ;; Rewrite the given input according to MAPPING, and return an input
      ;; in the format used in 'derivation' calls.
      (mlambda (input loop)
        (match input
          (($ <derivation-input> path (sub-drvs ...))
           (match (vhash-assoc path mapping)
             ((_ . (? derivation? replacement))
              (cons replacement sub-drvs))
             ((_ . replacement)
              (list replacement))
             (#f
              (let* ((drv (loop (call-with-input-file path read-derivation))))
                (cons drv sub-drvs))))))))

    (let loop ((drv drv))
      (let* ((inputs       (map (cut rewritten-input <> loop)
                                (derivation-inputs drv)))
             (initial      (append-map derivation-input-output-paths
                                       (derivation-inputs drv)))
             (replacements (append-map input->output-paths inputs))

             ;; Sources typically refer to the output directories of the
             ;; original inputs, INITIAL.  Rewrite them by substituting
             ;; REPLACEMENTS.
             (sources      (map (lambda (source)
                                  (match (vhash-assoc source mapping)
                                    ((_ . replacement)
                                     replacement)
                                    (#f
                                     (substitute-file source
                                                      initial replacements))))
                                (derivation-sources drv)))

             ;; Now augment the lists of initials and replacements.
             (initial      (append (derivation-sources drv) initial))
             (replacements (append sources replacements))
             (name         (store-path-package-name
                            (string-drop-right (derivation-file-name drv)
                                               4))))
        (derivation store name
                    (substitute (derivation-builder drv)
                                initial replacements)
                    (map (cut substitute <> initial replacements)
                         (derivation-builder-arguments drv))
                    #:system system
                    #:env-vars (map (match-lambda
                                     ((var . value)
                                      `(,var
                                        . ,(substitute value initial
                                                       replacements))))
                                    (derivation-builder-environment-vars drv))
                    #:inputs (append (map list sources) inputs)
                    #:outputs (derivation-output-names drv)
                    #:hash (match (derivation-outputs drv)
                             ((($ <derivation-output> _ algo hash))
                              hash)
                             (_ #f))
                    #:hash-algo (match (derivation-outputs drv)
                                  ((($ <derivation-output> _ algo hash))
                                   algo)
                                  (_ #f)))))))


;;;
;;; Store compatibility layer.
;;;

(define* (build-derivations store derivations
                            #:optional (mode (build-mode normal)))
  "Build DERIVATIONS, a list of <derivation> objects or .drv file names, using
the specified MODE."
  (build-things store (map (match-lambda
                            ((? string? file) file)
                            ((and drv ($ <derivation>))
                             (derivation-file-name drv)))
                           derivations)
                mode))


;;;
;;; Guile-based builders.
;;;

(define (parent-directories file-name)
  "Return the list of parent dirs of FILE-NAME, in the order in which an
`mkdir -p' implementation would make them."
  (let ((not-slash (char-set-complement (char-set #\/))))
    (reverse
     (fold (lambda (dir result)
             (match result
               (()
                (list dir))
               ((prev _ ...)
                (cons (string-append prev "/" dir)
                      result))))
           '()
           (remove (cut string=? <> ".")
                   (string-tokenize (dirname file-name) not-slash))))))

(define* (imported-files store files              ;deprecated
                         #:key (name "file-import")
                         (system (%current-system))
                         (guile (%guile-for-build)))
  "Return a derivation that imports FILES into STORE.  FILES must be a list
of (FINAL-PATH . FILE-NAME) pairs; each FILE-NAME is read from the file
system, imported, and appears under FINAL-PATH in the resulting store path."
  (let* ((files   (map (match-lambda
                        ((final-path . file-name)
                         (list final-path
                               (add-to-store store (basename final-path) #f
                                             "sha256" file-name))))
                       files))
         (builder
          `(begin
             (mkdir %output) (chdir %output)
             ,@(append-map (match-lambda
                            ((final-path store-path)
                             (append (match (parent-directories final-path)
                                       (() '())
                                       ((head ... tail)
                                        (append (map (lambda (d)
                                                       `(false-if-exception
                                                         (mkdir ,d)))
                                                     head)
                                                `((or (file-exists? ,tail)
                                                      (mkdir ,tail))))))
                                     `((symlink ,store-path ,final-path)))))
                           files))))
    (build-expression->derivation store name builder
                                  #:system system
                                  #:inputs files
                                  #:guile-for-build guile
                                  #:local-build? #t)))

;; The "file not found" error condition.
(define-condition-type &file-search-error &error
  file-search-error?
  (file     file-search-error-file-name)
  (path     file-search-error-search-path))

(define search-path*
  ;; A memoizing version of 'search-path' so 'imported-modules' does not end
  ;; up looking for the same files over and over again.
  (mlambda (path file)
    "Search for FILE in PATH and memoize the result.  Raise a
'&file-search-error' condition if it could not be found."
    (or (search-path path file)
        (raise (condition
                (&file-search-error (file file)
                                    (path path)))))))

(define (module->source-file-name module)
  "Return the file name corresponding to MODULE, a Guile module name (a list
of symbols.)"
  (string-append (string-join (map symbol->string module) "/")
                 ".scm"))

(define* (%imported-modules store modules         ;deprecated
                            #:key (name "module-import")
                            (system (%current-system))
                            (guile (%guile-for-build))
                            (module-path %load-path))
  "Return a derivation that contains the source files of MODULES, a list of
module names such as `(ice-9 q)'.  All of MODULES must be in the MODULE-PATH
search path."
  ;; TODO: Determine the closure of MODULES, build the `.go' files,
  ;; canonicalize the source files through read/write, etc.
  (let ((files (map (lambda (m)
                      (let ((f (module->source-file-name m)))
                        (cons f (search-path* module-path f))))
                    modules)))
    (imported-files store files #:name name #:system system
                    #:guile guile)))

(define* (%compiled-modules store modules         ;deprecated
                            #:key (name "module-import-compiled")
                            (system (%current-system))
                            (guile (%guile-for-build))
                            (module-path %load-path))
  "Return a derivation that builds a tree containing the `.go' files
corresponding to MODULES.  All the MODULES are built in a context where
they can refer to each other."
  (let* ((module-drv (%imported-modules store modules
                                        #:system system
                                        #:guile guile
                                        #:module-path module-path))
         (module-dir (derivation->output-path module-drv))
         (files      (map (lambda (m)
                            (let ((f (string-join (map symbol->string m)
                                                  "/")))
                              (cons (string-append f ".go")
                                    (string-append module-dir "/" f ".scm"))))
                      modules)))
    (define builder
      `(begin
         (use-modules (system base compile))
         (let ((out (assoc-ref %outputs "out")))
           (mkdir out)
           (chdir out))

         (set! %load-path
               (cons ,module-dir %load-path))

         ,@(map (match-lambda
                 ((output . input)
                  (let ((make-parent-dirs (map (lambda (dir)
                                                 `(unless (file-exists? ,dir)
                                                    (mkdir ,dir)))
                                               (parent-directories output))))
                   `(begin
                      ,@make-parent-dirs
                      (compile-file ,input
                                    #:output-file ,output
                                    #:opts %auto-compilation-options)))))
                files)))

    (build-expression->derivation store name builder
                                  #:inputs `(("modules" ,module-drv))
                                  #:system system
                                  #:guile-for-build guile
                                  #:local-build? #t)))

(define* (build-expression->derivation store name exp ;deprecated
                                       #:key
                                       (system (%current-system))
                                       (inputs '())
                                       (outputs '("out"))
                                       hash hash-algo recursive?
                                       (env-vars '())
                                       (modules '())
                                       guile-for-build
                                       references-graphs
                                       allowed-references
                                       disallowed-references
                                       local-build? (substitutable? #t))
  "Return a derivation that executes Scheme expression EXP as a builder
for derivation NAME.  INPUTS must be a list of (NAME DRV-PATH SUB-DRV)
tuples; when SUB-DRV is omitted, \"out\" is assumed.  MODULES is a list
of names of Guile modules from the current search path to be copied in
the store, compiled, and made available in the load path during the
execution of EXP.

EXP is evaluated in an environment where %OUTPUT is bound to the main
output path, %OUTPUTS is bound to a list of output/path pairs, and where
%BUILD-INPUTS is bound to an alist of string/output-path pairs made from
INPUTS.  Optionally, ENV-VARS is a list of string pairs specifying the
name and value of environment variables visible to the builder.  The
builder terminates by passing the result of EXP to `exit'; thus, when
EXP returns #f, the build is considered to have failed.

EXP is built using GUILE-FOR-BUILD (a derivation).  When GUILE-FOR-BUILD is
omitted or is #f, the value of the `%guile-for-build' fluid is used instead.

See the `derivation' procedure for the meaning of REFERENCES-GRAPHS,
ALLOWED-REFERENCES, DISALLOWED-REFERENCES, LOCAL-BUILD?, and SUBSTITUTABLE?."
  (define guile-drv
    (or guile-for-build (%guile-for-build)))

  (define guile
    (string-append (derivation->output-path guile-drv)
                   "/bin/guile"))

  (define module-form?
    (match-lambda
     (((or 'define-module 'use-modules) _ ...) #t)
     (_ #f)))

  (define source-path
    ;; When passed an input that is a source, return its path; otherwise
    ;; return #f.
    (match-lambda
     ((_ (? derivation?) _ ...)
      #f)
     ((_ path _ ...)
      (and (not (derivation-path? path))
           path))))

  (let* ((prologue `(begin
                      ,@(match exp
                          ((_ ...)
                           ;; Module forms must appear at the top-level so
                           ;; that any macros they export can be expanded.
                           (filter module-form? exp))
                          (_ `(,exp)))

                      (define %output (getenv "out"))
                      (define %outputs
                        (map (lambda (o)
                               (cons o (getenv o)))
                             ',outputs))
                      (define %build-inputs
                        ',(map (match-lambda
                                ((name drv . rest)
                                 (let ((sub (match rest
                                              (() "out")
                                              ((x) x))))
                                   (cons name
                                         (cond
                                          ((derivation? drv)
                                           (derivation->output-path drv sub))
                                          ((derivation-path? drv)
                                           (derivation-path->output-path drv
                                                                         sub))
                                          (else drv))))))
                               inputs))

                      ,@(if (null? modules)
                            '()
                            ;; Remove our own settings.
                            '((unsetenv "GUILE_LOAD_COMPILED_PATH")))

                      ;; Guile sets it, but remove it to avoid conflicts when
                      ;; building Guile-using packages.
                      (unsetenv "LD_LIBRARY_PATH")))
         (builder  (add-text-to-store store
                                      (string-append name "-guile-builder")

                                      ;; Explicitly use UTF-8 for determinism,
                                      ;; and also because UTF-8 output is faster.
                                      (with-fluids ((%default-port-encoding
                                                     "UTF-8"))
                                        (call-with-output-string
                                          (lambda (port)
                                            (write prologue port)
                                            (write
                                             `(exit
                                               ,(match exp
                                                  ((_ ...)
                                                   (remove module-form? exp))
                                                  (_ `(,exp))))
                                             port))))

                                      ;; The references don't really matter
                                      ;; since the builder is always used in
                                      ;; conjunction with the drv that needs
                                      ;; it.  For clarity, we add references
                                      ;; to the subset of INPUTS that are
                                      ;; sources, avoiding references to other
                                      ;; .drv; otherwise, BUILDER's hash would
                                      ;; depend on those, even if they are
                                      ;; fixed-output.
                                      (filter-map source-path inputs)))

         (mod-drv  (and (pair? modules)
                        (%imported-modules store modules
                                           #:guile guile-drv
                                           #:system system)))
         (mod-dir  (and mod-drv
                        (derivation->output-path mod-drv)))
         (go-drv   (and (pair? modules)
                        (%compiled-modules store modules
                                           #:guile guile-drv
                                           #:system system)))
         (go-dir   (and go-drv
                        (derivation->output-path go-drv))))
    (derivation store name guile
                `("--no-auto-compile"
                  ,@(if mod-dir `("-L" ,mod-dir) '())
                  ,builder)

                #:system system

                #:inputs `((,(or guile-for-build (%guile-for-build)))
                           (,builder)
                           ,@(map cdr inputs)
                           ,@(if mod-drv `((,mod-drv) (,go-drv)) '()))

                ;; When MODULES is non-empty, shamelessly clobber
                ;; $GUILE_LOAD_COMPILED_PATH.
                #:env-vars (if go-dir
                               `(("GUILE_LOAD_COMPILED_PATH" . ,go-dir)
                                 ,@(alist-delete "GUILE_LOAD_COMPILED_PATH"
                                                 env-vars))
                               env-vars)

                #:hash hash #:hash-algo hash-algo
                #:recursive? recursive?
                #:outputs outputs
                #:references-graphs references-graphs
                #:allowed-references allowed-references
                #:disallowed-references disallowed-references
                #:local-build? local-build?
                #:substitutable? substitutable?)))


;;;
;;; Monadic interface.
;;;

(define built-derivations
  (store-lift build-derivations))

(define raw-derivation
  (store-lift derivation))