Keep object locals only once in AST
For example this reduces the size of stdlib ast file
roughly 3x. Note that this change doesn't regenerate the stdlib,
so that the diff here is sane.
It is likely to slightly improve performance of code using
a lot of locals (~10% on bench.05.gen.jsonnet).
The desugaring is more strightforward now, and we're back
to desugaring each node exactly once.
* Interpreter & runtime - minimal usable version
Accomplishments in this commit:
* Majority of language features implemented:
* Unary operators
* Binary operators
* Conditionals
* Errors
* Indexing arrays
* Indexing objects
* Object inheritance
* Imports
* Functions
* Function calls
* There is a quite nice way for creating builtins
* Static analyzer is there with most of the functionality
* Standard library is included and parts unaffected by missing features
work
* Some bugs in existing parts fixed
* Most positive tests from C++ version pass, the rest is failing mostly
due to missing builtins and comprehensions.
* Some initial structure was created that should allow more incremental
and focused changes in the future PRs.
* Some comments/explanations added
* Panics translated to a little bit more gentle internal errors (with a
link to issues on github).
What still sucks:
* Stack traces & error messages (there's some stuff in place)
* Almost everything is in the same package
* Stuff is exported or unexporeted randomly (see above)
* Missing a few lexing/parsing features
* Missing builtins
* Missing support for extvars and top-level-args
* Checking function arguments is missing
* No clean Go API that commandline and compatibility layer to C can use
* No compatibility layer to C
* Assertions don't work (desugaring level, assertEquals works).
* Manifestation stack traces (and generally it could use some work).
* The way environments are constructed is sometimes suboptimal/clumsy.
