These changes make the Hy REPL more closely follow `code.InteractiveConsole`'s
class interface and provide minimally intrusive traceback print-out filtering
via a context manager that temporarily alters `sys.excepthook`. In other words,
exception messages from the REPL will no longer show Hy internal
code (e.g. importer, compiler and parsing functions).
The boolean variable `hy.errors._hy_filter_internal_errors` dynamically
enables/disables trace filtering, and the env variable
`HY_FILTER_INTERNAL_ERRORS` can be used as the initial value.
This commit refactors the exception/error classes and their handling.
It also retains Hy source strings and their originating file information, when
available, all throughout the core parser and compiler functions.
As well, with these changes, calling code is no longer responsible for providing
source and file details to exceptions,
Closeshylang/hy#657.
Functions and variables relating to compilation and parsing have been moved to
`compiler.py` and `lex/__init__.py`, respectively. Those functions are
- `hy_parse` from `hy.importer` to `hy.lex`
- `hy_eval`, `ast_compile`, and `calling_module` from `hy.importer` to
`hy.compiler`
Closeshylang/hy#1695.
This means that a HySymbol remembers its original name. That is, `a-b` and `a_b` are different symbols although `(setv a-b 1)` and `(setv a_b 1)` set the same variable (namely, `a_b`).
Most of the edits in this commit are to switch underscores to hyphens in places where mangling hasn't happened yet.
I removed some lexer tests since the lexer no longer does any mangling.
