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.
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.
permission to the Nix store or database. E.g., `nix-env -qa' will
work, but `nix-env -qas' won't (the latter needs DB access). The
option `--readonly-mode' forces this mode; otherwise, it's only
activated when the database cannot be opened.
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.
`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];
...