The code for serialization Expr nodes back into (pseudo-)Nix has been
removed for being subtly error-prone and tedious to maintain. Instead,
`nix-instantiate --parse` now prints a JSON representation of the AST.
Usage patterns of the --parse flag I've found in the wild:
1. Check if a file is well-formed, i.e. discard output and test exit code
2. Get parser errors from a file, i.e. discard stdout and use stderr
3. Nixfmt uses --parse to test equivalence pre/post format, and that property is (should be?) preserved
None of these should break with the current change
Closes#487
Change-Id: Icdbaad17790f2ad8765fa08e02e6597ee4c7a909
The old behavior results in lots of concatenations happening for no good
reason and is an artifact of the technical limitations of the old parser
(combined with some lack of care for such details).
Change-Id: I0d78d6220ca6aeaa10bc437e48e08bf7922e0bb3
This is only a minor semantical distinction, but we should be able to
properly test it, and the parser tests rely on show for that.
Change-Id: I25e868cf9544e30cdff17deb5fd50a434e0f367e