about summary refs log tree commit diff
path: root/src/libexpr/primops.cc
blob: 6b4858d800f1de3d8785a2158ef9856c48960824 (plain) (blame)
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
#include "build.hh"
#include "misc.hh"
#include "eval.hh"
#include "globals.hh"
#include "store.hh"
#include "util.hh"
#include "expr-to-xml.hh"
#include "nixexpr-ast.hh"

#include <algorithm>


namespace nix {


static Expr primBuiltins(EvalState & state, const ATermVector & args)
{
    /* Return an attribute set containing all primops.  This allows
       Nix expressions to test for new primops and take appropriate
       action if they're not available.  For instance, rather than
       calling a primop `foo' directly, they could say `if builtins ?
       foo then builtins.foo ... else ...'. */

    ATermMap builtins(128);

    for (ATermMap::const_iterator i = state.primOps.begin();
         i != state.primOps.end(); ++i)
    {
        string name = aterm2String(i->key);
        if (string(name, 0, 2) == "__")
            name = string(name, 2);
        /* !!! should use makePrimOp here, I guess. */
        builtins.set(toATerm(name), makeAttrRHS(makeVar(i->key), makeNoPos()));
    }

    return makeAttrs(builtins);
}


/* Load and evaluate an expression from path specified by the
   argument. */ 
static Expr primImport(EvalState & state, const ATermVector & args)
{
    PathSet context;
    Path path = coerceToPath(state, args[0], context);
    
    /* !!! build the derivations in context */

    return evalFile(state, path);
}


static Expr primPathExists(EvalState & state, const ATermVector & args)
{
    PathSet context;
    Path path = coerceToPath(state, args[0], context);
    if (!context.empty())
        throw EvalError(format("string `%1%' cannot refer to other paths") % path);
    return makeBool(pathExists(path));
}


/* Returns the hash of a derivation modulo fixed-output
   subderivations.  A fixed-output derivation is a derivation with one
   output (`out') for which an expected hash and hash algorithm are
   specified (using the `outputHash' and `outputHashAlgo'
   attributes).  We don't want changes to such derivations to
   propagate upwards through the dependency graph, changing output
   paths everywhere.

   For instance, if we change the url in a call to the `fetchurl'
   function, we do not want to rebuild everything depending on it
   (after all, (the hash of) the file being downloaded is unchanged).
   So the *output paths* should not change.  On the other hand, the
   *derivation store expression paths* should change to reflect the
   new dependency graph.

   That's what this function does: it returns a hash which is just the
   of the derivation ATerm, except that any input store expression
   paths have been replaced by the result of a recursive call to this
   function, and that for fixed-output derivations we return
   (basically) its outputHash. */
static Hash hashDerivationModulo(EvalState & state, Derivation drv)
{
    /* Return a fixed hash for fixed-output derivations. */
    if (drv.outputs.size() == 1) {
        DerivationOutputs::const_iterator i = drv.outputs.begin();
        if (i->first == "out" &&
            i->second.hash != "")
        {
            return hashString(htSHA256, "fixed:out:"
                + i->second.hashAlgo + ":"
                + i->second.hash + ":"
                + i->second.path);
        }
    }

    /* For other derivations, replace the inputs paths with recursive
       calls to this function.*/
    DerivationInputs inputs2;
    for (DerivationInputs::iterator i = drv.inputDrvs.begin();
         i != drv.inputDrvs.end(); ++i)
    {
        Hash h = state.drvHashes[i->first];
        if (h.type == htUnknown) {
            Derivation drv2 = derivationFromPath(i->first);
            h = hashDerivationModulo(state, drv2);
            state.drvHashes[i->first] = h;
        }
        inputs2[printHash(h)] = i->second;
    }
    drv.inputDrvs = inputs2;
    
    return hashTerm(unparseDerivation(drv));
}


/* Construct (as a unobservable side effect) a Nix derivation
   expression that performs the derivation described by the argument
   set.  Returns the original set extended with the following
   attributes: `outPath' containing the primary output path of the
   derivation; `drvPath' containing the path of the Nix expression;
   and `type' set to `derivation' to indicate that this is a
   derivation. */
static Expr primDerivationStrict(EvalState & state, const ATermVector & args)
{
    startNest(nest, lvlVomit, "evaluating derivation");

    ATermMap attrs(128); /* !!! */
    queryAllAttrs(evalExpr(state, args[0]), attrs, true);

    /* Figure out the name already (for stack backtraces). */
    Expr eDrvName = attrs.get(toATerm("name"));
    if (!eDrvName)
        throw EvalError("required attribute `name' missing");
    ATerm posDrvName;
    if (!matchAttrRHS(eDrvName, eDrvName, posDrvName)) abort();
    string drvName = evalStringNoCtx(state, eDrvName);

    /* Build the derivation expression by processing the attributes. */
    Derivation drv;
    
    PathSet context;

    string outputHash;
    string outputHashAlgo;
    bool outputHashRecursive = false;

    for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i) {
        string key = aterm2String(i->key);
        ATerm value;
        Expr pos;
        ATerm rhs = i->value;
        if (!matchAttrRHS(rhs, value, pos)) abort();
        startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);

        try {

            /* The `args' attribute is special: it supplies the
               command-line arguments to the builder. */
            if (key == "args") {
                ATermList es;
                value = evalExpr(state, value);
                if (!matchList(value, es)) {
                    static bool haveWarned = false;
                    warnOnce(haveWarned, "the `args' attribute should evaluate to a list");
                    es = flattenList(state, value);
                }
                for (ATermIterator i(es); i; ++i) {
                    string s = coerceToString(state, *i, context, true);
                    drv.args.push_back(s);
                }
            }

            /* All other attributes are passed to the builder through
               the environment. */
            else {
                string s = coerceToString(state, value, context, true);
                drv.env[key] = s;
                if (key == "builder") drv.builder = s;
                else if (key == "system") drv.platform = s;
                else if (key == "name") drvName = s;
                else if (key == "outputHash") outputHash = s;
                else if (key == "outputHashAlgo") outputHashAlgo = s;
                else if (key == "outputHashMode") {
                    if (s == "recursive") outputHashRecursive = true; 
                    else if (s == "flat") outputHashRecursive = false;
                    else throw EvalError(format("invalid value `%1%' for `outputHashMode' attribute") % s);
                }
            }

        } catch (Error & e) {
            e.addPrefix(format("while processing the derivation attribute `%1%' at %2%:\n")
                % key % showPos(pos));
            e.addPrefix(format("while instantiating the derivation named `%1%' at %2%:\n")
                % drvName % showPos(posDrvName));
            throw;
        }

    }
    
    /* Everything in the context of the strings in the derivation
       attributes should be added as dependencies of the resulting
       derivation. */
    for (PathSet::iterator i = context.begin(); i != context.end(); ++i) {
        debug(format("derivation uses `%1%'") % *i);
        assert(isStorePath(*i));
        if (isDerivation(*i))
            drv.inputDrvs[*i] = singleton<StringSet>("out");
        else
            drv.inputSrcs.insert(*i);
    }
            
    /* Do we have all required attributes? */
    if (drv.builder == "")
        throw EvalError("required attribute `builder' missing");
    if (drv.platform == "")
        throw EvalError("required attribute `system' missing");

    /* If an output hash was given, check it. */
    if (outputHash == "")
        outputHashAlgo = "";
    else {
        HashType ht = parseHashType(outputHashAlgo);
        if (ht == htUnknown)
            throw EvalError(format("unknown hash algorithm `%1%'") % outputHashAlgo);
        Hash h(ht);
        if (outputHash.size() == h.hashSize * 2)
            /* hexadecimal representation */
            h = parseHash(ht, outputHash);
        else if (outputHash.size() == hashLength32(h))
            /* base-32 representation */
            h = parseHash32(ht, outputHash);
        else
            throw Error(format("hash `%1%' has wrong length for hash type `%2%'")
                % outputHash % outputHashAlgo);
        string s = outputHash;
        outputHash = printHash(h);
        if (outputHashRecursive) outputHashAlgo = "r:" + outputHashAlgo;
    }

    /* Check whether the derivation name is valid. */
    checkStoreName(drvName);
    if (isDerivation(drvName))
        throw EvalError(format("derivation names are not allowed to end in `%1%'")
            % drvExtension);

    /* Construct the "masked" derivation store expression, which is
       the final one except that in the list of outputs, the output
       paths are empty, and the corresponding environment variables
       have an empty value.  This ensures that changes in the set of
       output names do get reflected in the hash. */
    drv.env["out"] = "";
    drv.outputs["out"] =
        DerivationOutput("", outputHashAlgo, outputHash);
        
    /* Use the masked derivation expression to compute the output
       path. */
    Path outPath = makeStorePath("output:out",
        hashDerivationModulo(state, drv), drvName);

    /* Construct the final derivation store expression. */
    drv.env["out"] = outPath;
    drv.outputs["out"] =
        DerivationOutput(outPath, outputHashAlgo, outputHash);

    /* Write the resulting term into the Nix store directory. */
    Path drvPath = writeDerivation(drv, drvName);

    printMsg(lvlChatty, format("instantiated `%1%' -> `%2%'")
        % drvName % drvPath);

    /* Optimisation, but required in read-only mode! because in that
       case we don't actually write store expressions, so we can't
       read them later. */
    state.drvHashes[drvPath] = hashDerivationModulo(state, drv);

    /* !!! assumes a single output */
    ATermMap outAttrs(2);
    outAttrs.set(toATerm("outPath"),
        makeAttrRHS(makeStr(outPath, singleton<PathSet>(drvPath)), makeNoPos()));
    outAttrs.set(toATerm("drvPath"),
        makeAttrRHS(makeStr(drvPath, singleton<PathSet>(drvPath)), makeNoPos()));

    return makeAttrs(outAttrs);
}


static Expr primDerivationLazy(EvalState & state, const ATermVector & args)
{
    Expr eAttrs = evalExpr(state, args[0]);
    ATermMap attrs(128); /* !!! */
    queryAllAttrs(eAttrs, attrs, true);

    attrs.set(toATerm("type"),
        makeAttrRHS(makeStr("derivation"), makeNoPos()));

    Expr drvStrict = makeCall(makeVar(toATerm("derivation!")), eAttrs);

    attrs.set(toATerm("outPath"),
        makeAttrRHS(makeSelect(drvStrict, toATerm("outPath")), makeNoPos()));
    attrs.set(toATerm("drvPath"),
        makeAttrRHS(makeSelect(drvStrict, toATerm("drvPath")), makeNoPos()));
    
    return makeAttrs(attrs);
}


/* Return the base name of the given string, i.e., everything
   following the last slash. */
static Expr primBaseNameOf(EvalState & state, const ATermVector & args)
{
    PathSet context;
    return makeStr(baseNameOf(coerceToPath(state, args[0], context)), context);
}


/* Return the directory of the given path, i.e., everything before the
   last slash.  Return either a path or a string depending on the type
   of the argument. */
static Expr primDirOf(EvalState & state, const ATermVector & args)
{
    PathSet context;
    Expr e = evalExpr(state, args[0]); ATerm dummy;
    bool isPath = matchPath(e, dummy);
    Path dir = dirOf(coerceToPath(state, e, context));
    return isPath ? makePath(toATerm(dir)) : makeStr(dir, context);
}


/* Convert the argument to a string.  Paths are *not* copied to the
   store, so `toString /foo/bar' yields `"/foo/bar"', not
   `"/nix/store/whatever..."'. */
static Expr primToString(EvalState & state, const ATermVector & args)
{
    PathSet context;
    string s = coerceToString(state, args[0], context, true, false);
    return makeStr(s, context);
}


/* Convert the argument to a path.  !!! obsolete? */
static Expr primToPath(EvalState & state, const ATermVector & args)
{
    PathSet context;
    string path = evalString(state, args[0], context);
    if (path == "" || path[0] != '/')
        throw EvalError("string doesn't represent an absolute path in `toPath'");
    return makeStr(canonPath(path), context);
}


/* Convert the argument (which can be any Nix expression) to an XML
   representation returned in a string.  Not all Nix expressions can
   be sensibly or completely represented (e.g., functions). */
static Expr primToXML(EvalState & state, const ATermVector & args)
{
    std::ostringstream out;
    PathSet context;
    printTermAsXML(strictEvalExpr(state, args[0]), out, context);
    return makeStr(out.str(), context);
}


/* Store a string in the Nix store as a source file that can be used
   as an input by derivations. */
static Expr primToFile(EvalState & state, const ATermVector & args)
{
    PathSet context;
    string name = evalStringNoCtx(state, args[0]);
    string contents = evalString(state, args[1], context);

    PathSet refs;

#if 0
    /* !!! */
    for (ATermIterator i(context); i; ++i) {
        ATerm s;
        if (matchPath(*i, s)) {
            assert(isStorePath(aterm2String(s)));
            refs.insert(aterm2String(s));
        }
        else throw EvalError("in `toFile': the file cannot contain references to derivation outputs");
    }
#endif    
    
    Path storePath = addTextToStore(name, contents, refs);

    /* Note: we don't need to add `context' to the context of the
       result, since `storePath' itself has references to the paths
       used in args[1]. */
    
    return makeStr(storePath, singleton<PathSet>(storePath));
}


/* Boolean constructors. */
static Expr primTrue(EvalState & state, const ATermVector & args)
{
    return eTrue;
}


static Expr primFalse(EvalState & state, const ATermVector & args)
{
    return eFalse;
}


/* Return the null value. */
static Expr primNull(EvalState & state, const ATermVector & args)
{
    return makeNull();
}


/* Determine whether the argument is the null value. */
static Expr primIsNull(EvalState & state, const ATermVector & args)
{
    return makeBool(matchNull(evalExpr(state, args[0])));
}


/* Determine whether the argument is a list. */
static Expr primIsList(EvalState & state, const ATermVector & args)
{
    ATermList list;
    return makeBool(matchList(evalExpr(state, args[0]), list));
}


static Path findDependency(Path dir, string dep)
{
    if (dep[0] == '/') throw EvalError(
        format("illegal absolute dependency `%1%'") % dep);

    Path p = canonPath(dir + "/" + dep);

    if (pathExists(p))
        return p;
    else
        return "";
}


/* Make path `p' relative to directory `pivot'.  E.g.,
   relativise("/a/b/c", "a/b/x/y") => "../x/y".  Both input paths
   should be in absolute canonical form. */
static string relativise(Path pivot, Path p)
{
    assert(pivot.size() > 0 && pivot[0] == '/');
    assert(p.size() > 0 && p[0] == '/');
        
    if (pivot == p) return ".";

    /* `p' is in `pivot'? */
    Path pivot2 = pivot + "/";
    if (p.substr(0, pivot2.size()) == pivot2) {
        return p.substr(pivot2.size());
    }

    /* Otherwise, `p' is in a parent of `pivot'.  Find up till which
       path component `p' and `pivot' match, and add an appropriate
       number of `..' components. */
    string::size_type i = 1;
    while (1) {
        string::size_type j = pivot.find('/', i);
        if (j == string::npos) break;
        j++;
        if (pivot.substr(0, j) != p.substr(0, j)) break;
        i = j;
    }

    string prefix;
    unsigned int slashes = count(pivot.begin() + i, pivot.end(), '/') + 1;
    while (slashes--) {
        prefix += "../";
    }

    return prefix + p.substr(i);
}


static Expr primDependencyClosure(EvalState & state, const ATermVector & args)
{
    startNest(nest, lvlDebug, "finding dependencies");

    Expr attrs = evalExpr(state, args[0]);

    /* Get the start set. */
    Expr startSet = queryAttr(attrs, "startSet");
    if (!startSet) throw EvalError("attribute `startSet' required");
    ATermList startSet2 = evalList(state, startSet);

    Path pivot;
    PathSet workSet;
    for (ATermIterator i(startSet2); i; ++i) {
        PathSet context; /* !!! what to do? */
        Path p = coerceToPath(state, *i, context);
        workSet.insert(p);
        pivot = dirOf(p);
    }

    /* Get the search path. */
    PathSet searchPath;
    Expr e = queryAttr(attrs, "searchPath");
    if (e) {
        ATermList list = evalList(state, e);
        for (ATermIterator i(list); i; ++i) {
            PathSet context; /* !!! what to do? */
            Path p = coerceToPath(state, *i, context);
            searchPath.insert(p);
        }
    }

    Expr scanner = queryAttr(attrs, "scanner");
    if (!scanner) throw EvalError("attribute `scanner' required");
    
    /* Construct the dependency closure by querying the dependency of
       each path in `workSet', adding the dependencies to
       `workSet'. */
    PathSet doneSet;
    while (!workSet.empty()) {
	Path path = *(workSet.begin());
	workSet.erase(path);

	if (doneSet.find(path) != doneSet.end()) continue;
        doneSet.insert(path);

        try {
            
            /* Call the `scanner' function with `path' as argument. */
            debug(format("finding dependencies in `%1%'") % path);
            ATermList deps = evalList(state, makeCall(scanner, makeStr(path)));

            /* Try to find the dependencies relative to the `path'. */
            for (ATermIterator i(deps); i; ++i) {
                string s = evalStringNoCtx(state, *i);
                
                Path dep = findDependency(dirOf(path), s);

                if (dep == "") {
                    for (PathSet::iterator j = searchPath.begin();
                         j != searchPath.end(); ++j)
                    {
                        dep = findDependency(*j, s);
                        if (dep != "") break;
                    }
                }
                
                if (dep == "")
                    debug(format("did NOT find dependency `%1%'") % s);
                else {
                    debug(format("found dependency `%1%'") % dep);
                    workSet.insert(dep);
                }
            }

        } catch (Error & e) {
            e.addPrefix(format("while finding dependencies in `%1%':\n")
                % path);
            throw;
        }
    }

    /* Return a list of the dependencies we've just found. */
    ATermList deps = ATempty;
    for (PathSet::iterator i = doneSet.begin(); i != doneSet.end(); ++i) {
        deps = ATinsert(deps, makeStr(relativise(pivot, *i)));
        deps = ATinsert(deps, makeStr(*i));
    }

    debug(format("dependency list is `%1%'") % makeList(deps));
    
    return makeList(deps);
}


static Expr primAbort(EvalState & state, const ATermVector & args)
{
    PathSet context;
    throw Abort(format("evaluation aborted with the following error message: `%1%'") %
        evalString(state, args[0], context));
}


/* Return the first element of a list. */
static Expr primHead(EvalState & state, const ATermVector & args)
{
    ATermList list = evalList(state, args[0]);
    if (ATisEmpty(list))
        throw Error("`head' called on an empty list");
    return evalExpr(state, ATgetFirst(list));
}


/* Return a list consisting of everything but the the first element of
   a list. */
static Expr primTail(EvalState & state, const ATermVector & args)
{
    ATermList list = evalList(state, args[0]);
    if (ATisEmpty(list))
        throw Error("`tail' called on an empty list");
    return makeList(ATgetNext(list));
}


/* Return an environment variable.  Use with care. */
static Expr primGetEnv(EvalState & state, const ATermVector & args)
{
    string name = evalStringNoCtx(state, args[0]);
    return makeStr(getEnv(name));
}


/* Apply a function to every element of a list. */
static Expr primMap(EvalState & state, const ATermVector & args)
{
    Expr fun = evalExpr(state, args[0]);
    ATermList list = evalList(state, args[1]);

    ATermList res = ATempty;
    for (ATermIterator i(list); i; ++i)
        res = ATinsert(res, makeCall(fun, *i));

    return makeList(ATreverse(res));
}


/* Return a string constant representing the current platform.  Note!
   that differs between platforms, so Nix expressions using
   `__currentSystem' can evaluate to different values on different
   platforms. */
static Expr primCurrentSystem(EvalState & state, const ATermVector & args)
{
    return makeStr(thisSystem);
}


static Expr primCurrentTime(EvalState & state, const ATermVector & args)
{
    return ATmake("Int(<int>)", time(0));
}


/* Dynamic version of the `.' operator. */
static Expr primGetAttr(EvalState & state, const ATermVector & args)
{
    string attr = evalStringNoCtx(state, args[0]);
    return evalExpr(state, makeSelect(args[1], toATerm(attr)));
}


/* Dynamic version of the `?' operator. */
static Expr primHasAttr(EvalState & state, const ATermVector & args)
{
    string attr = evalStringNoCtx(state, args[0]);
    return evalExpr(state, makeOpHasAttr(args[1], toATerm(attr)));
}


static Expr primRemoveAttrs(EvalState & state, const ATermVector & args)
{
    ATermMap attrs(128); /* !!! */
    queryAllAttrs(evalExpr(state, args[0]), attrs, true);
    
    ATermList list = evalList(state, args[1]);

    for (ATermIterator i(list); i; ++i)
        /* It's not an error for *i not to exist. */
        attrs.remove(toATerm(evalStringNoCtx(state, *i)));

    return makeAttrs(attrs);
}


static Expr primRelativise(EvalState & state, const ATermVector & args)
{
    PathSet context; /* !!! what to do? */
    Path pivot = coerceToPath(state, args[0], context);
    Path path = coerceToPath(state, args[1], context);
    return makeStr(relativise(pivot, path));
}


static Expr primAdd(EvalState & state, const ATermVector & args)
{
    int i1 = evalInt(state, args[0]);
    int i2 = evalInt(state, args[1]);
    return makeInt(i1 + i2);
}


static Expr primLessThan(EvalState & state, const ATermVector & args)
{
    int i1 = evalInt(state, args[0]);
    int i2 = evalInt(state, args[1]);
    return makeBool(i1 < i2);
}


void EvalState::addPrimOps()
{
    addPrimOp("builtins", 0, primBuiltins);
        
    addPrimOp("true", 0, primTrue);
    addPrimOp("false", 0, primFalse);
    addPrimOp("null", 0, primNull);
    addPrimOp("__currentSystem", 0, primCurrentSystem);
    addPrimOp("__currentTime", 0, primCurrentTime);

    addPrimOp("import", 1, primImport);
    addPrimOp("__pathExists", 1, primPathExists);
    addPrimOp("derivation!", 1, primDerivationStrict);
    addPrimOp("derivation", 1, primDerivationLazy);
    addPrimOp("baseNameOf", 1, primBaseNameOf);
    addPrimOp("dirOf", 1, primDirOf);
    addPrimOp("toString", 1, primToString);
    addPrimOp("__toPath", 1, primToPath);
    addPrimOp("__toXML", 1, primToXML);
    addPrimOp("isNull", 1, primIsNull);
    addPrimOp("__isList", 1, primIsList);
    addPrimOp("dependencyClosure", 1, primDependencyClosure);
    addPrimOp("abort", 1, primAbort);
    addPrimOp("__head", 1, primHead);
    addPrimOp("__tail", 1, primTail);
    addPrimOp("__getEnv", 1, primGetEnv);

    addPrimOp("map", 2, primMap);
    addPrimOp("__getAttr", 2, primGetAttr);
    addPrimOp("__hasAttr", 2, primHasAttr);
    addPrimOp("removeAttrs", 2, primRemoveAttrs);
    addPrimOp("relativise", 2, primRelativise);
    addPrimOp("__add", 2, primAdd);
    addPrimOp("__lessThan", 2, primLessThan);
    addPrimOp("__toFile", 2, primToFile);
}

 
}