Commit graph

456 commits

Author SHA1 Message Date
Eelco Dolstra 57d18df7d0 Add some support code for nix-repl 2013-09-02 18:34:04 +02:00
Eelco Dolstra 33972629d7 Fix whitespace 2013-09-02 16:29:15 +02:00
Shea Levy afc6c1bad6 Simplify inherited attribute handling
This reduces the difference between inherited and non-inherited
attribute handling to the choice of which env to use (in recs and lets)
by setting the AttrDef::e to a new ExprVar in the parser rather than
carrying a separate AttrDef::v VarRef member.

As an added bonus, this allows inherited attributes that inherit from a
with to delay forcing evaluation of the with's attributes.

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-08-26 11:31:56 +02:00
Ivan Kozik 34bb806f74 Fix typos, especially those that end up in the Nix manual 2013-08-26 11:15:22 +02:00
Eelco Dolstra d308aeaf53 Store Nix integers as longs
So on 64-bit systems, integers are now 64-bit.

Fixes #158.
2013-08-19 12:35:03 +02:00
Eelco Dolstra 46ffcce0c3 In the profiler output, show function names (if available) 2013-08-02 18:29:23 +00:00
Eelco Dolstra 159e621d1a Overload the ‘+’ operator to support integer addition 2013-08-02 15:21:17 +00:00
Eelco Dolstra 0a470fc345 Make Env smaller
Commit 20866a7031 added a ‘withAttrs’
field to Env, which is annoying because it makes every Env structure
bigger and we allocate millions of them.  E.g. NixOS evaluation took
18 MiB more.  So this commit squeezes ‘withAttrs’ into values[0].
Probably should use a union...
2013-07-31 12:44:21 +02:00
Eelco Dolstra 8ae6d55db1 Don't use NULL 2013-07-31 12:11:14 +02:00
Shea Levy e068f49f7d Avoid thunks when a fromWith var can be looked up without evaluation
Signed-off-by: Shea Levy <shea@shealevy.com>
2013-07-31 11:48:39 +02:00
Shea Levy 20866a7031 Delay evaulation of with attrs until a variable lookup needs them
Evaluation of attribute sets is strict in the attribute names, which
means immediate evaluation of `with` attribute sets rules out some
potentially interesting use cases (e.g. where the attribute names of one
set depend in some way on another but we want to bring those names into
scope for some values in the second set).

The major example of this is overridable self-referential package sets
(e.g. all-packages.nix). With immediate `with` evaluation, the only
options for such sets are to either make them non-recursive and
explicitly use the name of the overridden set in non-overridden one
every time you want to reference another package, or make the set
recursive and use the `__overrides` hack. As shown in the test case that
comes with this commit, though, delayed `with` evaluation allows a nicer
third alternative.

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-07-31 11:48:39 +02:00
Eelco Dolstra 18a48d80a0 Show function names in error messages
Functions in Nix are anonymous, but if they're assigned to a
variable/attribute, we can use the variable/attribute name in error
messages, e.g.

while evaluating `concatMapStrings' at `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/strings.nix:18:25':
...
2013-05-16 19:08:02 +02:00
Eelco Dolstra 1b3a03f161 Show which function argument was unexpected
Fixes #116.
2013-05-16 17:56:14 +02:00
Eelco Dolstra 229567293c Shut up a compiler warning 2013-05-16 17:48:19 +02:00
Eelco Dolstra bdd4646338 Revert "Prevent config.h from being clobbered"
This reverts commit 28bba8c44f.
2013-03-08 01:24:59 +01:00
Eelco Dolstra 28bba8c44f Prevent config.h from being clobbered 2013-03-07 23:55:55 +01:00
Eelco Dolstra 5f18cd2e84 Make "${./path} ..." evaluate to a string, not a path
Wacky string coercion semantics caused expressions like

  exec = "${./my-script} params...";

to evaluate to a path (‘/path/my-script params’), because
anti-quotations are desuged to string concatenation:

  exec = ./my-script + " params...";

By constrast, adding a space at the start would yield a string as
expected:

  exec = " ${./my-script} params...";

Now the first example also evaluates to a string.
2013-02-08 20:04:04 +01:00
Eelco Dolstra 8eed07cda4 nix-env -q --out-path: Support multiple outputs
We now print all output paths of a package, e.g.

  openssl-1.0.0i  bin=/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin;man=/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man;/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i

or (in XML mode)

  <item attrPath="openssl" name="openssl-1.0.0i" system="x86_64-linux">
    <output name="bin" path="/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin" />
    <output name="man" path="/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man" />
    <output name="out" path="/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i" />
  </item>
2012-11-28 13:49:44 +01:00
Eelco Dolstra 6c98e6a5de Optionally ignore null-valued derivation attributes
This allows adding attributes like

  attr = if stdenv.system == "bla" then something else null;

without changing the resulting derivation on non-<bla> platforms.

We once considered adding a special "ignore" value for this purpose,
but using null seems more elegant.
2012-11-27 15:01:32 +01:00
Eelco Dolstra 408a7bfac1 nix-instantiate: Fix read-only evaluation 2012-11-26 17:41:10 +01:00
Eelco Dolstra 88164325fa Fix a segfault when auto-calling a "a@{...}" function
Since the called function can return its argument attribute set
(e.g. "a"), the latter should not be allocated on the stack.

Reported by Shea.
2012-11-09 15:09:31 +01:00
Eelco Dolstra 0a7084567f Add a ‘--repair’ flag to nix-instantiate
This allows repairing corrupted derivations and other source files.
2012-10-03 15:09:18 -04:00
Eelco Dolstra 76e88871b2 Templatise tokenizeString() 2012-09-19 15:43:23 -04:00
Eelco Dolstra e94806d030 Merge branch 'master' into no-manifests 2012-08-27 11:09:07 -04:00
Eelco Dolstra 767101824a Avoid concatenating lists of one string 2012-08-13 15:10:29 -04:00
Eelco Dolstra e5c589d271 Don't allocate empty lists
This saves about 4 MB when evaluating a NixOS system configuration.
2012-08-13 15:02:09 -04:00
Eelco Dolstra 3e89ef597c Optimise concatenating a list to an empty list
More precisely, in concatLists, if all lists except one are empty,
then just return the non-empty list.  This reduces the number of list
element allocations by 32% when evaluating a NixOS system
configuration.
2012-08-13 14:58:54 -04:00
Eelco Dolstra 198d0338be Add a primop ‘concatLists’
This can serve as a generic efficient list builder.  For instance, the
function ‘catAttrs’ in Nixpkgs can be rewritten from

  attr: l: fold (s: l: if hasAttr attr s then [(getAttr attr s)] ++ l else l) [] l

to

  attr: l: builtins.concatLists (map (s: if hasAttr attr s then [(getAttr attr s)] else []) l)

Statistics before:

  time elapsed: 1.08683
  size of a value: 24
  environments allocated: 1384376 (35809568 bytes)
  list elements: 6946783 (55574264 bytes)
  list concatenations: 37434
  values allocated: 1760440 (42250560 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18273
  number of thunks: 1297673
  number of thunks avoided: 1380759
  number of attr lookups: 430802
  number of primop calls: 628912
  number of function calls: 1333544

Statistics after (including new catAttrs):

  time elapsed: 0.959854
  size of a value: 24
  environments allocated: 1010198 (26829296 bytes)
  list elements: 1984878 (15879024 bytes)
  list concatenations: 30488
  values allocated: 1589760 (38154240 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18274
  number of thunks: 1040925
  number of thunks avoided: 1038428
  number of attr lookups: 438419
  number of primop calls: 474844
  number of function calls: 959366
2012-08-13 01:53:10 -04:00
Eelco Dolstra 4ccd48ce24 Add a "filter" primop
Evaluation of a NixOS configuration spends quite a lot of time in the
"filter" function in Nixpkgs.  As implemented in Nixpkgs, this is a
O(n^2) operation, so it's a good candidate for providing a more
efficient (i.e. primop) implementation.  Using it gives a ~10% speed
increase and a significant reduction in the number of evaluations.

Statistics before (on a NixOS system config):

  time elapsed: 1.3258
  size of a value: 24
  environments allocated: 1980939 (50127080 bytes)
  list elements: 14679308 (117434464 bytes)
  list concatenations: 50828
  values allocated: 2098938 (50374512 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18271
  number of thunks: 1645752
  number of thunks avoided: 1921196
  number of attr lookups: 430798
  number of primop calls: 838807
  number of function calls: 1930107

Statistics after:

  time elapsed: 1.17982
  size of a value: 24
  environments allocated: 1543334 (39624560 bytes)
  list elements: 9612638 (76901104 bytes)
  list concatenations: 37434
  values allocated: 1854933 (44518392 bytes)
  attribute sets allocated: 392040
  right-biased unions: 186334
  values copied in right-biased unions: 591137
  symbols in symbol table: 18272
  number of thunks: 1392467
  number of thunks avoided: 1507311
  number of attr lookups: 430801
  number of primop calls: 691600
  number of function calls: 1492502
2012-08-13 00:28:08 -04:00
Eelco Dolstra 62f72eb9e1 Add some more evaluations stats 2012-08-12 23:41:48 -04:00
Eelco Dolstra e82767910c Add some basic profiling support to the evaluator
Setting the environment variable NIX_COUNT_CALLS to 1 enables some
basic profiling in the evaluator.  It will count calls to functions
and primops as well as evaluations of attributes.

For example, to see where evaluation of a NixOS configuration spends
its time:

$ NIX_SHOW_STATS=1 NIX_COUNT_CALLS=1 ./src/nix-instantiate/nix-instantiate '<nixos>' -A system --readonly-mode
...
calls to 39 primops:
    239532 head
    233962 tail
    191252 hasAttr
...
calls to 1595 functions:
    224157 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:19'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:14'
    221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:10'
...
evaluations of 7088 attributes:
    167377 undefined position
    132459 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:119:41'
     47322 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:13:21'
...
2012-08-12 23:29:28 -04:00
Eelco Dolstra 97421eb5ec Refactor settings processing
Put all Nix configuration flags in a Settings object.
2012-07-30 19:55:41 -04:00
Eelco Dolstra 1217204c81 Remove dead code 2012-07-17 14:07:52 -04:00
Eelco Dolstra f491ae97d4 * Inline some functions and get rid of the indirection through
EvalState::eval().  This gives a 12% speedup on ‘nix-instantiate
  /etc/nixos/nixos/ -A system --readonly-mode’ (from 1.01s to 0.89s).
2012-02-04 13:50:25 +00:00
Eelco Dolstra 2bda12ef3b * Print elapsed evaluation time. 2012-02-04 13:27:11 +00:00
Eelco Dolstra 330df4b4db * Allow comparisons between derivations by comparing the outPath
attributes.
2012-01-19 23:08:47 +00:00
Eelco Dolstra 9fe24c5a0d * Don't create thunks for simple constants (integers, strings, paths)
and allocate them only once.
* Move Value and related functions into value.hh.
2012-01-07 17:26:33 +00:00
Eelco Dolstra b52966e821 * Remove dead code. 2012-01-04 21:47:48 +00:00
Eelco Dolstra 35f2a6ba82 * Don't use dynamic_cast, it's very slow. "nix-instantiate
/etc/nixos/nixos -A system" spent about 10% of its time in
  dynamic_cast.
2012-01-04 21:24:11 +00:00
Eelco Dolstra 921111d197 * Move the implementation of the ‘derivation’ primop into a separate
file.
2012-01-03 14:01:47 +00:00
Shea Levy 24b65937e1 Remove the unused sCurrentOutput symbol 2011-11-06 06:28:34 +00:00
Shea Levy 2721e9f56f Merge from trunk 2011-11-06 00:13:09 +00:00
Eelco Dolstra a12095d3be * In printValueAsXML, handle the case where a "type" attribute is not
a string.  This happens in the NixOS option system.
* Remove a bogus comparison of a unsigned integer with -1.
2011-10-27 19:06:23 +00:00
Shea Levy ffa038f66d Add an sCurrentOutput member to EvalState 2011-09-16 11:30:44 +00:00
Eelco Dolstra 2d663b502d * Cache the result of file evaluation (i.e, memoize evalFile()). This
prevents files from being evaluated and stored as values multiple
  times.  For instance, evaluation of the ‘system’ attribute in NixOS
  causes ‘nixpkgs/pkgs/lib/lists.nix’ to be evaluated 2019 times.

  Caching gives a modest speedup and a decent memory footprint
  reduction (e.g., from 1.44s to 1.28s, and from 81 MiB to 59 MiB with
  GC_INITIAL_HEAP_SIZE=100000 on my system).
2011-08-06 19:45:43 +00:00
Eelco Dolstra 00a724ebc6 * Remove a debug statement. 2011-08-06 18:24:43 +00:00
Eelco Dolstra 07340b8be7 * Add the Nix corepkgs to the end of the search path. This makes it
possible for other Nix expressions to use corepkgs (mostly useful
  for the buildenv function).
2011-08-06 18:23:38 +00:00
Eelco Dolstra 1ecc97b6bd * Add a Nix expression search path feature. Paths between angle
brackets, e.g.

    import <nixpkgs/pkgs/lib>

  are resolved by looking them up relative to the elements listed in
  the search path.  This allows us to get rid of hacks like

    import "${builtins.getEnv "NIXPKGS_ALL"}/pkgs/lib"

  The search path can be specified through the ‘-I’ command-line flag
  and through the colon-separated ‘NIX_PATH’ environment variable,
  e.g.,

    $ nix-build -I /etc/nixos ...

  If a file is not found in the search path, an error message is
  lazily thrown.
2011-08-06 16:05:24 +00:00
Eelco Dolstra 54945a2950 * Refactoring: move parseExprFromFile() and parseExprFromString() into
the EvalState class.
2011-08-06 13:02:55 +00:00
Eelco Dolstra 0a623a10c7 * Allow a default value in attribute selection by writing
x.y.z or default

  (as originally proposed in
  https://mail.cs.uu.nl/pipermail/nix-dev/2009-September/002989.html).

  For instance, an expression like

    stdenv.lib.attrByPath ["features" "ckSched"] false args

  can now be written as

    args.features.ckSched or false
2011-07-13 12:19:57 +00:00
Eelco Dolstra 2b9e29b1c8 * Change the right-hand side of the ‘.’ operator from an attribute to
an attribute path.  This is a refactoring to support default values.
2011-07-06 12:28:57 +00:00
Eelco Dolstra 5637037802 * In the ‘?’ operator, allow attribute paths. For instance, you can
write ‘attrs ? a.b’ to test whether ‘attrs’ has an attribute ‘a’
  containing an attribute ‘b’.  This is more convenient than ‘attrs ?
  a && attrs.a ? b’.

  Slight change in the semantics: it's no longer an error if the
  left-hand side of ‘?’ is not an attribute set.  In that case it just
  returns false.  So, ‘null ? foo’ no longer throws an error.
2011-07-06 10:58:17 +00:00
Eelco Dolstra 538b7caab0 * Don't allocate a big initial GC address space on machines with
little RAM.  Even if the memory isn't actually used, it can cause
  problems with the overcommit heuristics in the kernel.  So use a VM
  space of 25% of RAM, up to 384 MB.
2011-02-10 14:31:04 +00:00
Eelco Dolstra 5a6b039802 * Don't call GC_expand_hp unless we're actually using the garbage
collector.
2011-02-09 22:59:50 +00:00
Eelco Dolstra 0c4828ea05 * new(UseGC) is inexplicably slower than GC_MALLOC, so prefer the
latter.
2010-10-28 12:50:01 +00:00
Eelco Dolstra e11e6fb1c6 * Handle out of memory condition. 2010-10-28 12:29:40 +00:00
Eelco Dolstra 43535499f3 * When allocating an attribute set, reserve enough space for all
elements.  This prevents the vector from having to resize itself.
2010-10-24 20:09:37 +00:00
Eelco Dolstra e0b7fb8f27 * Keep attribute sets in sorted order to speed up attribute lookups.
* Simplify the representation of attributes in the AST.
* Change the behaviour of listToAttrs() in case of duplicate names.
2010-10-24 19:52:33 +00:00
Eelco Dolstra 2dc6d50941 * Don't create thunks for variable lookups (if possible). This
significantly reduces the number of values allocated (e.g. from 8.7m
  to 4.9m for the Bittorrent test).
2010-10-24 14:20:02 +00:00
Eelco Dolstra 0b305c534f * Store attribute sets as a vector instead of a map (i.e. a red-black
tree).  This saves a lot of memory.  The vector should be sorted so
  that names can be looked up using binary search, but this is not the
  case yet.  (Surprisingly, looking up attributes using linear search
  doesn't have a big impact on performance.)

  Memory consumption for

    $ nix-instantiate /etc/nixos/nixos/tests -A bittorrent.test --readonly-mode

  on x86_64-linux with GC enabled is now 185 MiB (compared to 946
  MiB on the trunk).
2010-10-24 00:41:29 +00:00
Eelco Dolstra a247d20604 * Fix compiling without Boehm.
* Fix the stats.
2010-10-23 22:58:24 +00:00
Eelco Dolstra b2ba62170c * Optimise string constants by putting them in the symbol table. 2010-10-23 21:11:59 +00:00
Eelco Dolstra 8ac06726b9 * Make Value smaller by not storing redundant PrimOp info.
* Clear pointers in Values after overwriting them to make sure that no
  objects are kept alive unnecessarily.
2010-10-23 20:07:47 +00:00
Eelco Dolstra 3f66cfb96b * Remove allocValues(). 2010-10-23 18:18:07 +00:00
Eelco Dolstra 4dee289550 * In environments, store pointers to values rather than values. This
improves GC effectiveness a bit more (because a live value doesn't
  keep other values in the environment plus the parent environments
  alive), and removes the need for copy nodes.
2010-10-22 15:51:52 +00:00
Eelco Dolstra 41c45a9b31 * Store Value nodes outside of attribute sets. I.e., Attr now stores
a pointer to a Value, rather than the Value directly.  This improves
  the effectiveness of garbage collection a lot: if the Value is
  stored inside the set directly, then any live pointer to the Value
  causes all other attributes in the set to be live as well.
2010-10-22 14:47:42 +00:00
Eelco Dolstra 64c3325b0b * Make building against the Boehm GC a configure option. 2010-10-22 13:39:15 +00:00
Eelco Dolstra 76feaf016a * Keep some more stats. 2010-10-20 15:48:00 +00:00
Eelco Dolstra e879a0371b * Use the Boehm garbage collector to reclaim unused memory in the Nix
expression evaluator.
2010-10-20 11:38:30 +00:00
Eelco Dolstra df50916e46 * Oops - "null" was displayed as "true". 2010-08-27 12:10:56 +00:00
Eelco Dolstra 6d6200f37a * Optimisation in the // operator: if one of the sets is empty, return
the other set.
2010-08-02 16:31:05 +00:00
Eelco Dolstra f16fe2af8d * builtins.toXML: propagate the string context. This is a regression
from the old ATerm-based evaluator.
2010-06-10 10:29:50 +00:00
Eelco Dolstra 1ab67cf437 2010-06-02 09:43:04 +00:00
Eelco Dolstra 93cd5a4a13 * The << operator on values should be const. 2010-05-18 10:36:37 +00:00
Eelco Dolstra b2235d81d1 * Restore the __overrides feature that was lost somewhere in the
fast-eval branch.
2010-05-15 08:10:12 +00:00
Eelco Dolstra bd25ac2260 * Print attributes in sorted order. 2010-05-12 12:15:49 +00:00
Eelco Dolstra 01e58adce0 * Store position info for inherited attributes. 2010-05-07 12:43:57 +00:00
Eelco Dolstra e2d5e40f4f * Keep track of the source positions of attributes. 2010-05-07 12:11:05 +00:00
Eelco Dolstra 84ce7ac76f * Store attribute positions in the AST and report duplicate attribute
errors with position info.
* For all positions, use the position of the first character of the
  first token, rather than the last character of the first token plus
  one.
2010-05-06 16:46:48 +00:00
Eelco Dolstra 0bc468f195 * Simplify the implementation of `with'. This gives a 7% speedup in
evaluating the NixOS system configuration.
2010-04-22 15:08:09 +00:00
Eelco Dolstra 2d7636529f * String equality tests should take the context into account. All the
evaluation test cases now succeed.
2010-04-22 09:54:11 +00:00
Eelco Dolstra 0777448ca6 * Fixed builtins.genericClosure. 2010-04-21 15:57:11 +00:00
Eelco Dolstra fe2d869e04 * Store user environment manifests as a Nix expression in
$out/manifest.nix rather than as an ATerm.

  (Hm, I thought I committed this two days ago...)
2010-04-21 15:08:58 +00:00
Eelco Dolstra 5c31995bb8 * Updated some more primops. 2010-04-16 15:13:47 +00:00
Eelco Dolstra 8ca4a001cb * Improve sharing a bit. 2010-04-16 14:03:26 +00:00
Eelco Dolstra 497e4ad126 * Remove some redundant tests. 2010-04-16 13:51:01 +00:00
Eelco Dolstra 02c1dac909 * In an nested with' where the inner with is a variable (with ...;
with someVar; ...'), the contents of the variable would be
  clobbered.  (The attributes in the outer `with' were added to the
  variable.)
2010-04-16 13:44:02 +00:00
Eelco Dolstra 04c4bd3624 * Store lists as lists of pointers to values rather than as lists of
values.  This improves sharing and gives another speed up.
  Evaluation of the NixOS system attribute is now almost 7 times
  faster than the old evaluator.
2010-04-15 00:37:36 +00:00
Eelco Dolstra e41b5828db * Better stats. 2010-04-14 23:48:46 +00:00
Eelco Dolstra d39d3c6264 * Implemented inherit. 2010-04-14 23:25:05 +00:00
Eelco Dolstra 267dc693d2 * Fix builtins. 2010-04-14 22:59:39 +00:00
Eelco Dolstra 81de12bc8f * Refactoring: move variable uses to a separate class. 2010-04-14 15:14:23 +00:00
Eelco Dolstra 110d155778 * Implemented withs. 2010-04-14 15:01:04 +00:00
Eelco Dolstra 9985230c00 * After parsing, compute level/displacement pairs for each variable
use site, allowing environments to be stores as vectors of values
  rather than maps.  This should speed up evaluation and reduce the
  number of allocations.
2010-04-14 14:42:32 +00:00
Eelco Dolstra 85d13c8f93 * Change the semantics of "with" so that inner "withs" take
precedence, i.e. `with {x=1;}; with {x=2;}; x' evaluates to 2'.
  This has a simpler implementation and seems more natural.  There
  doesn't seem to be any code in Nixpkgs or NixOS that relies on the
  old behaviour.
2010-04-14 08:37:08 +00:00
Eelco Dolstra 816f9c0f6f * Use std::tr1::unordered_set instead of std::set for the symbol
table.  This gives a 10% speed increase on `nix-instantiate
  /etc/nixos/nixos -A system --readonly-mode'.
2010-04-13 14:34:11 +00:00
Eelco Dolstra 7d47498b5e * Evaluate lets directly (i.e. without desugaring to `rec { attrs...;
<let-body> = e; }.<let-body>).  This prevents the unnecessary
  allocation of an attribute set.
2010-04-13 13:42:25 +00:00
Eelco Dolstra ac1e8f40d4 * Use a symbol table to represent identifiers and attribute names
efficiently.  The symbol table ensures that there is only one copy
  of each symbol, thus allowing symbols to be compared efficiently
  using a pointer equality test.
2010-04-13 12:25:42 +00:00
Eelco Dolstra 10e8b1fd15 * Finished the ATerm-less parser. 2010-04-12 23:33:23 +00:00
Eelco Dolstra d4f0b0fc6c * Indented strings. 2010-04-12 22:03:27 +00:00
Eelco Dolstra a60317f20f * More missing constructs. 2010-04-12 21:21:24 +00:00
Eelco Dolstra 4d6ad5be17 * Don't use ATerms for the abstract syntax trees anymore. Not
finished yet.
2010-04-12 18:30:11 +00:00
Eelco Dolstra db90b88e65 * Hack to support builderDefs expressions. 2010-04-12 09:50:20 +00:00
Eelco Dolstra 4e49002576 * Doh. 2010-04-12 09:45:00 +00:00
Eelco Dolstra f3dc7ab877 * Keep more statistics about stack space usage.
* Reduce stack space usage.
2010-04-09 12:00:49 +00:00
Eelco Dolstra b7b3dd55f9 * Remove a lot of dead code. 2010-04-08 11:41:19 +00:00
Eelco Dolstra 7e048eddf5 * Fix blackholing. If evaluation fails due to an assertion failure,
then the blackhole has to be removed to ensure that repeated
  evaluation of the same value gives an assertion failure again rather
  than an "infinite recursion" error.
2010-04-08 11:25:14 +00:00
Eelco Dolstra af2a372bb0 * Update autoCallFunction() and findAlongAttrPath(). 2010-04-07 15:47:06 +00:00
Eelco Dolstra fc92244ba8 * Implemented the primops necessary for generating the NixOS manual. 2010-04-07 13:55:46 +00:00
Eelco Dolstra a353aef0b1 * In eval(), don't use the target value `v' as a temporary.
Overwriting `v' breaks when the expression evaluation to an
  assertion failure or throw.
2010-04-06 14:15:29 +00:00
Eelco Dolstra c172274e17 * Quick hack to make coerceToString work more or less correctly on
nested lists.  `nix-instantiate' can now evaluate the NixOS system
  derivation attribute correctly (in 2.1s on my laptop vs. 6.2s for
  the trunk).
2010-04-01 14:35:03 +00:00
Eelco Dolstra 7b851915bf * Improve sharing. 2010-04-01 12:04:57 +00:00
Eelco Dolstra 95cc417d76 * Functions are incomparable. 2010-04-01 10:55:36 +00:00
Eelco Dolstra 71f026292b * Make `derivation' lazy again for performance. It also turns out
that there are some places in Nixpkgs (php_configurable /
  composableDerivation, it seems) that call `derivation' with
  incorrect arguments (namely, the `name' attribute missing) but get
  away with it because of laziness.
2010-04-01 09:55:57 +00:00
Eelco Dolstra dc31305b38 * Fixed the trace primop and path comparison.
* Removed exprToString and stringToExpr because there is no ATerm
  representation to work on anymore (and exposing the internals of the
  evaluator like this is not a good idea anyway).
2010-03-31 20:09:20 +00:00
Eelco Dolstra 979f163615 * Handle string contexts. `nix-instantiate' can now correctly compute
the `firefoxWrapper' attribute in Nixpkgs, and it's about 3 times
  faster than the trunk :-)
2010-03-31 19:52:29 +00:00
Eelco Dolstra 55e207b2dc * Cache parse trees to prevent repeated parsing of imported Nix
expressions.
2010-03-31 16:14:32 +00:00
Eelco Dolstra 3d94be61ea * Implemented derivations. 2010-03-31 15:38:03 +00:00
Eelco Dolstra 13c2adc897 * Implemented `rec { inherit ...; }'. 2010-03-31 11:05:39 +00:00
Eelco Dolstra 4c53ca2692 * Compare nulls. 2010-03-31 09:54:12 +00:00
Eelco Dolstra 7f19e03c65 * More primops. 2010-03-30 22:39:48 +00:00
Eelco Dolstra 47df476daa * More operators / primops. 2010-03-30 18:05:54 +00:00
Eelco Dolstra c9170be2bd * More primops. 2010-03-30 15:18:20 +00:00
Eelco Dolstra c3aa615a5f * More primops. 2010-03-30 14:39:27 +00:00
Eelco Dolstra 5b72d8a749 * Implemented `map'. 2010-03-30 13:47:59 +00:00
Eelco Dolstra d78a05ab40 * Make `import' work. 2010-03-30 09:22:33 +00:00
Eelco Dolstra 31428c3a06 * Started integrating the new evaluator. 2010-03-29 14:37:56 +00:00
Eelco Dolstra 8a10360c91 * Simplify @-patterns: only {attrs}@name' or name@{attrs}' are now
allowed.  So `name1@name2', `{attrs1}@{attrs2}' and so on are now no
  longer legal.  This is no big loss because they were not useful
  anyway.

  This also changes the output of builtins.toXML for @-patterns
  slightly.
2010-03-25 12:19:41 +00:00
Eelco Dolstra 50d11b90ca * Allow unsafe (unspecified) comparisons between attrsets unless
NIX_NO_UNSAFE_EQ is set, for now.
2009-05-12 11:06:24 +00:00
Eelco Dolstra c34e6d71bc * Disallow equality tests between attribute sets. This was always
broken, but now the evaluator checks for it to prevent Nix
  expressions from relying on undefined behaviour.  Equality tests are
  implemented using a shallow pointer equality test between ATerms.
  However, because attribute sets are lazy and contain position
  information, this can give false positives.  For instance,
  previously

    let y = {x = 1;}; in y == y

  evaluated to true, while the equivalent expression

    {x = 1;} == {x = 1;}

  evaluated to false.  So disallow these tests for now.  (Eventually
  we may want to implement deep equality tests for attribute sets,
  like lib.eqStrict.)
  
* Idem: disallow comparisons between functions.

* Implemented deep comparisons of lists.  This had the same problem as
  attribute sets - the elements in the list weren't evaluated.  For
  instance,

    ["xy"] == [("x" + "y")]

  evaluated to false.  Now it works properly.
2009-05-11 15:50:14 +00:00
Eelco Dolstra 99dc3e613a * Require that __overrides is defined as a non-recursive attribute
(which means it can only be defined via "inherit"), otherwise we get
  scoping bugs, since __overrides can't be recursive (or at least, it
  would be hard).
2008-08-26 14:05:59 +00:00
Michael Raskin b7ff182b6e Fixing an obvious typo in override code. I do not know whether it works correctly after the change, but at least it ca nbe compiled now. 2008-08-14 22:01:43 +00:00
Eelco Dolstra ca07f3e370 * Another experimental feature: a way to truly override attributes in
a rec.  This will be very useful to allow end-user customisation of
  all-packages.nix, for instance globally overriding GCC or some other
  dependency.  The // operator doesn't cut it: you could replace the
  "gcc" attribute, but all other attributes would continue to
  reference the original value due to the substitution semantics of
  rec.

  The syntax is a bit hacky but this is to allow backwards
  compatibility.
2008-08-14 16:59:37 +00:00
Eelco Dolstra 9279174dde * Added an experimental feature suggested by Andres: ellipses ("...")
in attribute set pattern matches.  This allows defining a function
  that takes *at least* the listed attributes, while ignoring
  additional attributes.  For instance,

    {stdenv, fetchurl, fuse, ...}:
    
    stdenv.mkDerivation {
      ...
    };
    
  defines a function that requires an attribute set that contains the 
  specified attributes but ignores others.  The main advantage is that
  we can then write in all-packages.nix

    aefs = import ../bla/aefs pkgs;

  instead of

    aefs = import ../bla/aefs {
      inherit stdenv fetchurl fuse;
    };

  This saves a lot of typing (not to mention not having to update
  all-packages.nix with purely mechanical changes).  It saves as much
  typing as the "args: with args;" style, but has the advantage that
  the function arguments are properly declared (not implicit in what
  the body of the "with" uses).
2008-08-14 14:00:44 +00:00
Eelco Dolstra 1b962fc720 * @-patterns as in Haskell. For instance, in a function definition
f = args @ {x, y, z}: ...;

  `args' refers to the argument as a whole, which is further
  pattern-matched against the attribute set pattern {x, y, z}.
2008-08-14 12:53:29 +00:00
Eelco Dolstra efe4b690ae * Refactoring: combine functions that take an attribute set and
functions that take a single argument (plain lambdas) into one AST
  node (Function) that contains a Pattern node describing the
  arguments.  Current patterns are single lazy arguments (VarPat) and
  matching against an attribute set (AttrsPat).

  This refactoring allows other kinds of patterns to be added easily,
  such as Haskell-style @-patterns, or list pattern matching.
2008-08-14 10:04:22 +00:00
Eelco Dolstra 5664b6d7ba * Removed the "valid values" feature. Nobody uses it anyway. 2008-08-11 13:36:40 +00:00
Eelco Dolstra fc691e1cbd * Print a better error message when a non-derivation attribute set is
coerced to a string.
2008-07-24 14:52:25 +00:00
Eelco Dolstra bddc83a148 * New builtin function "isFunction". You're not supposed to use it
;-)
* Channels: fix channels that are plain lists of derivations (like
  strategoxt-unstable) instead  of functions (like nixpkgs-unstable).
  This fixes the error message "error: the left-hand side of the
  function call is neither a function nor a primop (built-in
  operation) but a list".
2007-05-16 16:17:04 +00:00
Eelco Dolstra 5f2492eaec * New primop "throw <string>" to throw an error. This is like abort,
only thrown errors are caught by the top-level derivation evaluation
  in nix-env -qa / -i.
2007-04-16 15:03:19 +00:00
Eelco Dolstra 044b6482c1 * Greatly reduced the amount of stack space used by the Nix expression
evaluator.  This was important because the NixOS expressions started
  to hit 2 MB default stack size on Linux.

  GCC is really dumb about stack space: it just adds up all the local
  variables and temporaries of every scope into one huge stack frame.
  This is really bad for deeply recursive functions.  For instance,
  every `throw Error(format("error message"))' causes a format object
  of a few hundred bytes to be allocated on the stack.  As a result,
  every recursive call to evalExpr2() consumed 4680 bytes.  By
  splitting evalExpr2() and by moving the exception-throwing code out
  of the main functions, evalExpr2() now only consumes 40 bytes.
  Similar for evalExpr().
2007-02-27 19:10:45 +00:00
Eelco Dolstra adce01a8d0 * When NIX_SHOW_STATS=1, show the amount of stack space consumed by
the Nix expression evaluator.
2007-02-27 17:28:51 +00:00
Eelco Dolstra 05879db628 * Memoize strict evaluation. 2007-01-13 15:41:54 +00:00
Eelco Dolstra 792878af91 * Make printing an expression as XML interruptible. 2007-01-13 14:48:41 +00:00
Eelco Dolstra 11158028be * Cleanup. 2007-01-13 14:21:49 +00:00
Eelco Dolstra a824d58b56 * Merge addToStore and addToStoreFixed.
* addToStore now adds unconditionally, it doesn't use readOnlyMode.
  Read-only operation is up to the caller (who can call
  computeStorePathForPath).
2006-12-01 20:51:18 +00:00
Eelco Dolstra e2ef5e07fd * Refactoring. There is now an abstract interface class StoreAPI
containing functions that operate on the Nix store.  One
  implementation is LocalStore, which operates on the Nix store
  directly.  The next step, to enable secure multi-user Nix, is to
  create a different implementation RemoteStore that talks to a
  privileged daemon process that uses LocalStore to perform the actual
  operations.
2006-11-30 17:43:04 +00:00
Eelco Dolstra 4bd5cdb90b * Print out the offending path. 2006-10-17 14:01:28 +00:00
Eelco Dolstra 58ff6939f4 * An awful backwards compatibility hack. 2006-10-17 12:58:42 +00:00
Eelco Dolstra 7de5fe2fc2 * Do the path check on the normal form. 2006-10-17 10:57:25 +00:00
Eelco Dolstra d7efd76394 * Big cleanup of the semantics of paths, strings, contexts, string
concatenation and string coercion.  This was a big mess (see
  e.g. NIX-67).  Contexts are now folded into strings, so that they
  don't cause evaluation errors when they're not expected.  The
  semantics of paths has been clarified (see nixexpr-ast.def).
  toString() and coerceToString() have been merged.

  Semantic change: paths are now copied to the store when they're in a
  concatenation (and in most other situations - that's the
  formalisation of the meaning of a path).  So

    "foo " + ./bla

  evaluates to "foo /nix/store/hash...-bla", not "foo
  /path/to/current-dir/bla".  This prevents accidental impurities, and
  is more consistent with the treatment of derivation outputs, e.g.,
  `"foo " + bla' where `bla' is a derivation.  (Here `bla' would be
  replaced by the output path of `bla'.)
2006-10-16 15:55:34 +00:00
Eelco Dolstra 7d4567f2cc * Removed URIs from the evaluator (NIX-66). They are now just another
kind of notation for strings.
2006-10-11 21:59:33 +00:00
Eelco Dolstra 0c4c5c2020 * Quick hack to fix NIX-67: evaluation result differing if the Nix
expression resides in the store.
2006-10-10 21:23:35 +00:00
Eelco Dolstra d20c3011a0 * toFile: added an additional argument to specify the store path
suffix, e.g., `builtins.toFile "builder.sh" "..."'.
* toFile: handle references to other files correctly.
2006-10-03 14:55:54 +00:00
Eelco Dolstra e347033f71 * The result of a concatenation with a derivation on the left-hand
side should be a path, I guess.
* Handle paths that are in the store but not direct children of the
  store directory.
* Ugh, hack to prevent double context wrapping.
2006-09-24 21:39:57 +00:00
Eelco Dolstra 2ab4bc44c7 * Builtin function `add' to add integers.
* Put common test functions in tests/lang/lib.nix.
2006-09-22 15:29:21 +00:00
Eelco Dolstra 75068e7d75 * Use a proper namespace.
* Optimise header file usage a bit.
* Compile the parser as C++.
2006-09-04 21:06:23 +00:00
Eelco Dolstra f93f7b75be * Okay, that's a bit harder than expected. 2006-08-30 13:10:04 +00:00
Eelco Dolstra 3151bdea55 * Uninitialised variable. 2006-08-30 12:00:27 +00:00
Eelco Dolstra 2132d9ddeb * Fix the ~ operator. 2006-08-29 15:29:38 +00:00
Eelco Dolstra 1fca76870b * Removed processBinding, instead we now apply toString to all
derivation attributes to flatten them into strings.  This is
  possible since string can nowadays be wrapped in contexts that
  describe the derivations/sources referenced by the evaluation of the
  string.
2006-08-28 13:31:06 +00:00
Eelco Dolstra da25d80152 * Strict evaluation and XML printing of lists. 2006-08-24 14:03:39 +00:00
Eelco Dolstra 943ab38a0d * Refactoring: move strictEval to libexpr. 2006-08-24 13:39:22 +00:00
Eelco Dolstra 38f18aa6d4 * New primop: abort "error message". 2006-08-23 15:46:00 +00:00
Eelco Dolstra 1854f84e83 * Fix a few warnings. 2006-08-04 17:07:13 +00:00
Eelco Dolstra 4661282fde * `nix-instantiate ... --arg NAME VALUE': allow arguments to be passed
to functions from the command line.
* nix-build: started removing backticks.
2006-07-28 16:03:28 +00:00
Eelco Dolstra ca2238cf81 * Refactoring: get the selection path stuff out of getDerivations()
and put it into a separate function findAlongAttrPath().
2006-07-26 15:05:15 +00:00
Eelco Dolstra 7a3a5d1608 * When there is a domain check, we have to evaluate the argument.
Can't be lazy!
2006-07-24 16:49:28 +00:00
Eelco Dolstra f4c5531d92 * New language feature: domain checks, which check whether a function
argument has a valid value, i.e., is in a certain domain.  E.g.,

    { foo : [true false]
    , bar : ["a" "b" "c"]
    }: ...

  This previously could be done using assertions, but domain checks
  will allow the buildfarm to automatically extract the configuration
  space from functions.
2006-07-24 16:35:34 +00:00
Eelco Dolstra 57751fdb55 * Refactoring to support domain checks. 2006-07-24 15:16:03 +00:00
Eelco Dolstra 4f3725b167 * Better error messages (especially wrt types). 2006-07-19 15:36:15 +00:00
Eelco Dolstra 5cabd47394 * Allow function argument default values to refer to other arguments
of the function.  Implements NIX-45.
2006-05-08 12:52:47 +00:00
Eelco Dolstra 310e605995 * Show evaluation stats when NIX_SHOW_STATS=1. 2006-05-08 10:00:37 +00:00
Eelco Dolstra 0832956089 * Use the new ATermMap. 2006-05-04 12:21:08 +00:00
Eelco Dolstra d300b4383d * Optimise null-ary term builders. Also declare all term builder
functions as pure, which might improve performance a bit.
2006-05-02 21:58:46 +00:00
Eelco Dolstra 68174bdc7d * Use a linked list of substitutions. This reduces the amount of
copying.
2006-05-02 21:39:02 +00:00
Eelco Dolstra dc719e6ba5 * Some preliminaries towards NIX-45. 2006-05-02 13:39:55 +00:00
Eelco Dolstra 0064599a27 * String interpolation. Expressions like
"--with-freetype2-library=" + freetype + "/lib"

  can now be written as

    "--with-freetype2-library=${freetype}/lib"

  An arbitrary expression can be enclosed within ${...}, not just
  identifiers.

* Escaping in string literals: \n, \r, \t interpreted as in C, any
  other character following \ is interpreted as-is.
  
* Newlines are now allowed in string literals.
2006-05-01 14:01:47 +00:00
Eelco Dolstra 6cecad2be0 * Allow string concatenations involving derivations, e.g.,
configureFlags = "--with-freetype2-library="
      + freetype + "/lib";
2006-05-01 09:56:56 +00:00
Eelco Dolstra 2b3b6c9b34 * In theory, this should reduce the number of ATermMap
re-allocations.
2006-03-10 16:14:13 +00:00
Eelco Dolstra 6dca5c9099 * When obtaining derivations from Nix expressions, ignore all
expressions that cause an assertion failure (like `assert system ==
  "i686-linux"').  This allows all-packages.nix in Nixpkgs to be used
  on all platforms, even if some Nix expressions don't work on all
  platforms.

  Not sure if this is a good idea; it's a bit hacky.  In particular,
  due to laziness some derivations might appear in `nix-env -qa' but
  disappear in `nix-env -qas' or `nix-env -i'.

  Commit 5000!
2006-03-08 16:03:58 +00:00
Eelco Dolstra 9088dee9e2 * Some refactoring of the exception handling code so that we can catch
Nix expression assertion failures.
2006-03-08 14:11:19 +00:00
Eelco Dolstra 991a130b1e * Added a list concatenation operator:
[1 2 3] ++ [4 5 6] => [1 2 3 4 5 6]
2005-07-25 15:05:34 +00:00
Eelco Dolstra cb7ccb528b * string2ATerm -> overloaded toATerm. 2004-11-03 18:12:03 +00:00
Eelco Dolstra a69534fc21 * Drop ATmake / ATMatcher also in handling store expressions. 2004-10-29 11:22:49 +00:00
Eelco Dolstra 5fe9222b36 * Don't use ATmake / ATmatch anymore, nor the ATMatcher class.
Instead we generate data bindings (build and match functions) for
  the constructors specified in `constructors.def'.  In particular
  this removes the conversions between AFuns and strings, and Nix
  expression evaluation now seems 3 to 4 times faster.
2004-10-26 22:54:26 +00:00
Eelco Dolstra 033d7c6593 * Doh! 2004-10-26 17:04:55 +00:00
Eelco Dolstra 9fa07b376d * String/path concatenation operator (`+'). 2004-10-26 17:01:35 +00:00
Eelco Dolstra 37d7abd694 * New language feature: with expressions.
The expression `with E1; E2' evaluates to E2 with all bindings in
  the attribute set E1 substituted.  E.g.,

    with {x = 123;}; x

  evaluates to 123.  That is, the attribute set E1 is in scope in E2.

  This is particularly useful when importing files containing lots
  definitions.  E.g., instead of

    let {
      inherit (import ./foo.nix) a b c d e f;

      body = ... a ... f ...;
    }

  we can now say

    with import ./foo.nix;

    ... a ... f ...

  I.e., we don't have to say what variables should be brought into scope.
2004-10-25 16:54:56 +00:00
Eelco Dolstra d8989b1fb4 * Every real language has a `map' function. 2004-08-04 11:27:53 +00:00
Eelco Dolstra bbfdd64741 * Allow primops with more that 1 arguments. 2004-08-04 10:59:20 +00:00
Eelco Dolstra 59b94ee18a * When something goes wrong in the evaluation of a Nix expression,
print a nice backtrace of the stack, rather than vomiting a gigantic
  (and useless) aterm on the screen.  Example:

    error: while evaluating file `.../pkgs/system/test.nix':
    while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
    while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
    assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13

  Since the Nix expression language is lazy, the trace may be
  misleading.  The purpose is to provide a hint as to the location of
  the problem.
2004-04-05 22:27:41 +00:00
Eelco Dolstra c4ac2a164a * The recent change in nixpkgs of calling `stdenv.mkDerivation'
instead of `derivation' triggered a huge slowdown in the Nix
  expression evaluator.  Total execution time of `nix-env -qa' went up
  by a factor of 60 or so.

  This scalability problem was caused by expressions such as

    (x: y: ... x ...) a b

  where `a' is a large term (say, the one in
  `all-packages-generic.nix').  Then the first beta-reduction would
  produce

    (y: ... a ...) b

  by substituting `a' for `x'.  The second beta-reduction would then
  substitute `b' for `y' into the body `... a ...', which is a large
  term due to `a', and thus causes a large traversal to be performed
  by substitute() in the second reduction.  This is however entirely
  redundant, since `a' cannot contain free variables (since we never
  substitute below a weak head normal form).

  The solution is to wrap substituted terms into a `Closed'
  constructor, i.e.,

    subst(subs, Var(x)) = Closed(e) iff subs[x] = e

  have substitution not descent into closed terms,

    subst(subs, Closed(x)) = Closed(x)

  and otherwise ignore them for evaluation,

    eval(Closed(x)) = eval(x).

* Fix a typo that caused incorrect substitutions to be performed in
  simple lambdas, e.g., `(x: x: x) a' would reduce to `(x: a)'.
2004-03-30 15:05:35 +00:00
Eelco Dolstra ac4d39f9db * Added an operator `?' to test for attribute existence, e.g.,
`attrs ? x' yields true iff `attrs' has an attribute named `x'.
2004-03-28 21:15:01 +00:00
Eelco Dolstra f958bcdf1f * Added an operator `~' to select paths within a derivation. E.g.,
{stdenv, bash}: derivation {
      builder = bash ~ /bin/sh;
      args = ["-e" "-x" ./builder.sh];
      ...
    }

  Here the attribute `builder' will evaluate to, e.g.,
  `/nix/store/1234abcd...-bash-2.0.1/bin/sh'.
2004-03-28 20:58:28 +00:00
Eelco Dolstra db3e644c1c * Added plain lambdas, e.g., `let { id = x: x; const = x: y: x; }'.
`bla:' is now no longer parsed as a URL.

* Re-enabled support for the `args' attribute in derivations to
  specify command line arguments to the builder, e.g.,

    ...
    builder = /usr/bin/python;
    args = ["-c" ./builder.py];
    ...
2004-03-28 20:34:22 +00:00
Eelco Dolstra 79bb0008ec * `null' is a normal form. 2004-03-19 14:45:45 +00:00
Eelco Dolstra fbc48a469c * Inherited attributes in recursive attribute sets are in scope of the
non-inherited attributes.
2004-02-16 09:18:35 +00:00
Eelco Dolstra 9d25466b34 * An attribute set update operator (//). E.g.,
{x=1; y=2; z=3;} // {y=4;}  =>  {x=1; y=4; z=3;}
2004-02-04 16:49:51 +00:00
Eelco Dolstra 9b44480612 * Use a map to lookup primops.
* Various performance improvements in the evaluator.
* Do not link against unused (and missing!) libraries (-lsglr, etc.).
2004-02-04 16:03:29 +00:00
Eelco Dolstra c4f7ae4aa5 * Verify that all variables in a Nix expression are defined. 2004-02-03 14:45:34 +00:00
Eelco Dolstra 1c9c0a5a46 * Added syntactic sugar to the construction of attribute sets to
`inherit' variables from the surrounding lexical scope.

  E.g.,

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      inherit stdenv libfoo;
      xyzzy = 1;
    }

  is equivalent to

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      stdenv = stdenv;
      libfoo = libfoo;
      xyzzy = 1;
    }

  Note that for mutually recursive attribute set definitions (`rec
  {...}'), this also works, that is, `rec {inherit x;}' is equivalent
  to `let {fresh = x; body = rec {x = fresh;};}', *not*
  `rec {x = x}'.
2004-02-02 21:39:33 +00:00
Eelco Dolstra c5baaafae6 * Replaced the SDF parser by a substantially faster Bison/Flex
parser (roughly 80x faster).

  The absolutely latest version of Bison (1.875c) is required for
  reentrant GLR support, as well as a recent version of Flex (say,
  2.5.31).  Note that most Unix distributions ship with the
  prehistoric Flex 2.5.4, which doesn't support reentrancy.
2004-01-30 15:21:42 +00:00
Eelco Dolstra 447089a5f6 * Catch SIGINT to terminate cleanly when the user tries to interrupt
Nix.  This is to prevent Berkeley DB from becoming wedged.

  Unfortunately it is not possible to throw C++ exceptions from a
  signal handler.  In fact, you can't do much of anything except
  change variables of type `volatile sig_atomic_t'.  So we set an
  interrupt flag in the signal handler and check it at various
  strategic locations in the code (by calling checkInterrupt()).
  Since this is unlikely to cover all cases (e.g., (semi-)infinite
  loops), sometimes SIGTERM may now be required to kill Nix.
2004-01-15 20:23:55 +00:00
Eelco Dolstra 6e8c19714a * Allow integer bindings in derivations. 2003-11-25 12:05:48 +00:00
Eelco Dolstra ac68840e79 * Refactoring: put the Nix expression evaluator in its own library so
that it can be used by multiple programs.
2003-11-19 11:35:41 +00:00
Renamed from src/nix-instantiate/eval.cc (Browse further)