Commit graph

116 commits

Author SHA1 Message Date
Eelco Dolstra 9bedd9b09b Remove obsolete reference to ~ operator 2015-02-19 14:41:22 +01:00
Eelco Dolstra 153a943de7 Show position info for failing <...> lookups 2015-01-07 13:43:55 +01:00
Eelco Dolstra 4e0607369e Pedantry 2014-12-14 01:51:14 +01:00
Eelco Dolstra b6809608cc Get rid of some unnecessary ExprConcatStrings nodes in dynamic attrs
This gives a ~18% speedup in NixOS evaluation (after converting
most calls to hasAttr/getAttr to dynamic attrs).
2014-10-05 01:04:58 +02:00
Eelco Dolstra 11849a320e Use proper quotes everywhere 2014-08-20 18:03:48 +02:00
Eelco Dolstra 3d221a7bb1 Rename nixPath to __nixPath
The name ‘nixPath’ breaks existing code.
2014-07-30 11:28:39 +02:00
Eelco Dolstra d8c061e044 Remove ExprBuiltin
It's slower than ExprVar since it doesn't compute a static
displacement. Since we're not using the throw primop in the
implementation of <...> anymore, it's also not really needed.
2014-05-26 17:14:28 +02:00
Eelco Dolstra 62a6eeb1f3 Make the Nix search path declarative
Nix search path lookups like <nixpkgs> are now desugared to ‘findFile
nixPath <nixpkgs>’, where ‘findFile’ is a new primop. Thus you can
override the search path simply by saying

  let
    nixPath = [ { prefix = "nixpkgs"; path = "/my-nixpkgs"; } ];
  in ... <nixpkgs> ...

In conjunction with ‘scopedImport’ (commit
c273c15cb1), the Nix search path can be
propagated across imports, e.g.

  let

    overrides = {
      nixPath = [ ... ] ++ builtins.nixPath;
      import = fn: scopedImport overrides fn;
      scopedImport = attrs: fn: scopedImport (overrides // attrs) fn;
      builtins = builtins // overrides;
    };

  in scopedImport overrides ./nixos
2014-05-26 17:02:22 +02:00
Eelco Dolstra 39d72640c2 Ensure that -I flags get included in nixPath
Also fixes #261.
2014-05-26 16:52:31 +02:00
Eelco Dolstra c273c15cb1 Add primop ‘scopedImport’
‘scopedImport’ works like ‘import’, except that it takes a set of
attributes to be added to the lexical scope of the expression,
essentially extending or overriding the builtin variables.  For
instance, the expression

  scopedImport { x = 1; } ./foo.nix

where foo.nix contains ‘x’, will evaluate to 1.

This has a few applications:

* It allows getting rid of function argument specifications in package
  expressions. For instance, a package expression like:

    { stdenv, fetchurl, libfoo }:

    stdenv.mkDerivation { ... buildInputs = [ libfoo ]; }

  can now we written as just

    stdenv.mkDerivation { ... buildInputs = [ libfoo ]; }

  and imported in all-packages.nix as:

    bar = scopedImport pkgs ./bar.nix;

  So whereas we once had dependencies listed in three places
  (buildInputs, the function, and the call site), they now only need
  to appear in one place.

* It allows overriding builtin functions. For instance, to trace all
  calls to ‘map’:

  let
    overrides = {
      map = f: xs: builtins.trace "map called!" (map f xs);

      # Ensure that our override gets propagated by calls to
      # import/scopedImport.
      import = fn: scopedImport overrides fn;

      scopedImport = attrs: fn: scopedImport (overrides // attrs) fn;

      # Also update ‘builtins’.
      builtins = builtins // overrides;
    };
  in scopedImport overrides ./bla.nix

* Similarly, it allows extending the set of builtin functions. For
  instance, during Nixpkgs/NixOS evaluation, the Nixpkgs library
  functions could be added to the default scope.

There is a downside: calls to scopedImport are not memoized, unlike
import. So importing a file multiple times leads to multiple parsings
/ evaluations. It would be possible to construct the AST only once,
but that would require careful handling of variables/environments.
2014-05-26 14:26:29 +02:00
Eelco Dolstra 8e5fbf4d73 Show position info in attribute selection errors 2014-04-04 22:52:14 +02:00
Eelco Dolstra 4c5faad994 Show position info in Boolean operations 2014-04-04 22:43:52 +02:00
Eelco Dolstra bd9b1d97b4 Show position info in string concatenation / addition errors 2014-04-04 22:19:33 +02:00
Eelco Dolstra c28de6d96e Pass position information to primop calls
For example:

  error: `tail' called on an empty list, at
    /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/ex-2/default.nix:13:7
2014-04-04 18:59:29 +02:00
Eelco Dolstra b72c8d2e5b Include position info in function application
This allows error messages like:

  error: the anonymous function at `/etc/nixos/configuration.nix:1:1'
    called without required argument `foo', at
    `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/lib/modules.nix:77:59'
2014-04-04 18:59:29 +02:00
Shea Levy 049a379ec6 The expr of AttrNames/DynamicAttrDefs is always an ExprConcatStrings 2014-03-10 10:14:50 +01:00
Eelco Dolstra f14ef84a51 Warn about missing -I paths
Fixes #121.  Note that we don't warn about missing $NIX_PATH entries
because it's intended that some may be missing (cf. the default
$NIX_PATH on NixOS, which includes paths like /etc/nixos/nixpkgs for
backward compatibility).
2014-02-26 15:21:56 +01:00
Eelco Dolstra 94f9c14d52 Fix some clang warnings 2014-01-21 18:29:55 +01:00
Eelco Dolstra 68cde53c47 Fix building against Bison 3.0.2 2014-01-21 15:34:04 +01:00
Shea Levy f5e5793cd2 Bare dynamic attrs: Match interpolation semantics
Signed-off-by: Shea Levy <shea@shealevy.com>
2014-01-14 14:00:15 +01:00
Shea Levy f9913f4422 Allow "bare" dynamic attrs
Now, in addition to a."${b}".c, you can write a.${b}.c (applicable
wherever dynamic attributes are valid).

Signed-off-by: Shea Levy <shea@shealevy.com>
2014-01-14 14:00:15 +01:00
Shea Levy cd49fe4f9b Don't use any syntactic sugar for dynamic attrs
This doesn't change any functionality but moves some behavior out of the
parser and into the evaluator in order to simplify the code.

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-12-31 23:56:26 +00:00
Shea Levy 6f3a51809a Fold dynamic binds handling into addAttr
Since addAttr has to iterate through the AttrPath we pass it, it makes
more sense to just iterate through the AttrNames in addAttr instead. As
an added bonus, this allows attrsets where two dynamic attribute paths
have the same static leading part (see added test case for an example
that failed previously).

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-12-31 17:57:10 -05:00
Shea Levy 18fefacf7d Dynamic attrs
This adds new syntax for attribute names:

* attrs."${name}" => getAttr name attrs
* attrs ? "${name}" => isAttrs attrs && hasAttr attrs name
* attrs."${name}" or def => if attrs ? "${name}" then attrs."${name}" else def
* { "${name}" = value; } => listToAttrs [{ inherit name value; }]

Of course, it's a bit more complicated than that. The attribute chains
can be arbitrarily long and contain combinations of static and dynamic
parts (e.g. attrs."${foo}".bar."${baz}" or qux), which is relatively
straightforward for the getAttrs/hasAttrs cases but is more complex for
the listToAttrs case due to rules about duplicate attribute definitions.

For attribute sets with dynamic attribute names, duplicate static
attributes are detected at parse time while duplicate dynamic attributes
are detected when the attribute set is forced. So, for example, { a =
null; a.b = null; "${"c"}" = true; } will be a parse-time error, while
{ a = {}; "${"a"}".b = null; c = true; } will be an eval-time error
(technically that case could theoretically be detected at parse time,
but the general case would require full evaluation). Moreover, duplicate
dynamic attributes are not allowed even in cases where they would be
with static attributes ({ a.b.d = true; a.b.c = false; } is legal, but {
a."${"b"}".d = true; a."${"b"}".c = false; } is not). This restriction
might be relaxed in the future in cases where the static variant would
not be an error, but it is not obvious that that is desirable.

Finally, recursive attribute sets with dynamic attributes have the
static attributes in scope but not the dynamic ones. So rec { a = true;
"${"b"}" = a; } is equivalent to { a = true; b = true; } but rec {
"${"a"}" = true; b = a; } would be an error or use a from the
surrounding scope if it exists.

Note that the getAttr, getAttr or default, and hasAttr are all
implemented purely in the parser as syntactic sugar, while attribute
sets with dynamic attribute names required changes to the AST to be
implemented cleanly.

This is an alternative solution to and closes #167

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-12-31 20:59:49 +00:00
Shea Levy 136f2f7046 Add the ExprBuiltin Expr type to the AST
Certain desugaring schemes may require the parser to use some builtin
function to do some of the work (e.g. currently `throw` is used to
lazily cause an error if a `<>`-style path is not in the search path)
Unfortunately, these names are not reserved keywords, so an expression
that uses such a syntactic sugar will not see the expected behavior
(see tests/lang/eval-okay-redefine-builtin.nix for an example).

This adds the ExprBuiltin AST type, which when evaluated uses the value
from the rootmost variable scope (which of course is initialized
internally and can't shadow any of the builtins).

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-12-31 17:45:47 +00:00
Eelco Dolstra fc33fd86b7 Add a symbol __curPos that expands to the current source location
I.e. an attribute set { file = <string>; line = <int>; column = <int>; }.
2013-11-18 20:16:02 +01:00
Eelco Dolstra b8034e5581 Ensure proper type checking/coercion of "${expr}"
Now we only rewrite "${expr}" to expr if expr is a string literal.
2013-10-17 00:57:24 +02:00
Eelco Dolstra 9deb822180 Deduplicate filenames in Pos
This saves ~4 MiB of RAM for NixOS system instantiation, and ~18 MiB
for "nix-env -qa".
2013-10-08 15:36:10 +02:00
Eelco Dolstra 6b47de580f Show the exact position of undefined variables
In particular, undefined variable errors in a "with" previously didn't
show *any* position information, so this should help a lot in those
cases.
2013-10-08 14:40:51 +02:00
Eelco Dolstra 6f809194d7 Get rid of the parse tree cache
Since we already cache files in normal form (fileEvalCache), caching
parse trees is redundant.

Note that getting rid of this cache doesn't actually save much memory
at the moment, because parse trees are currently not freed / GC'ed.
2013-09-03 13:01:42 +02:00
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
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 3d77b28eac Add comparison operators ‘<’, ‘<=’, ‘>’ and ‘>=’ 2013-08-02 18:39:40 +02:00
Eelco Dolstra 47701677e8 Add integer ‘-’, ‘*’ and ‘/’ operators 2013-08-02 16:03:02 +00:00
Eelco Dolstra 5d147e125c Add a unary integer negation operator
This allows saying "-1" instead of "builtins.sub 0 1".
2013-08-02 15:43:31 +00:00
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 804709706c Fix building against Bison 2.6 2013-03-14 18:31:08 +01:00
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 767101824a Avoid concatenating lists of one string 2012-08-13 15:10:29 -04:00
Eelco Dolstra 00c98a6bef Use Bison 2.5 2012-04-13 14:28:26 +02:00
Eelco Dolstra 9d091ee99a * Handle the case where the search path element is a regular file. 2011-08-06 18:45:28 +00:00
Eelco Dolstra c7101dac0b * Allow redirections in search path entries. E.g. if you have a
directory

    /home/eelco/src/stdenv-updates

  that you want to use as the directory for import such as

    with (import <nixpkgs> { });

  then you can say

    $ nix-build -I nixpkgs=/home/eelco/src/stdenv-updates
2011-08-06 17:48:57 +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 d5d4dcd4c9 * Allow attribute names to be strings. Based on the
allow-arbitrary-strinsg-in-names patch by Marc Weber.
2011-07-13 15:53:24 +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