0a84137c45
undefined variables by definition. This matters for the implementation of "with", which does a call to checkVarDefs to see if the body of the with has no undefined variables. (It can't be checked at parse time because you don't know which variables are in the "with" attribute set.) If we check closed terms, then we check not just the with body but also the substituted terms, which are typically very large. This is the cause of the poor nix-env performance on Nixpkgs lately. It didn't happen earlier because "with" wasn't used very often in the past. This fix improves nix-env performance roughly 60x on current Nixpkgs. nix-env -qa is down from 29.3s to 0.5s on my laptop, and nix-env -qa --out-path is down from 229s to 3.39s. Not bad for a 1-line fix :-)
For installation and usage instructions, please read the manual, which can be found in `docs/manual/manual.html', and additionally at the Nix website at <http://www.cs.uu.nl/groups/ST/Trace/Nix>. Acknowledgments This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)