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.
Previously, when importing `hy` (and any of its sub-packages/modules), Hy source
compilation for `hy.core.language` was necessarily triggered. This, in turn,
would trigger compilation of the other standard library source files.
This commit removes that chain of events and allows the `hy` package to be
imported without any Hy compilation.
Furthermore, `read` and `read_str` are now implemented in Python and the Hy
standard library files now handle their own dependencies explicitly (i.e. they
`import` and/or `require` the other standard library files upon which they
depend).
The latter changes were necessary, because the automatically triggered
compilation of `hy.core.language` (and associated standard library files) was
serving--implicitly--as a means of producing bytecode in an order that just
happened to work for any compilation occurring afterward. This chain of
events/dependencies was extremely cryptic, brittle, and difficult to debug, and
these changes should help to remedy that.
Closeshylang/hy#1697.
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.
- Expose `read`, `read_str`, and `eval` in Python
- Add string evaluation example to interop section of docs
- Add test for `eval`
- Explain `eof` keyword argument in `read` docstring
