Compiler and command-line error messages now reflect their Python counterparts.
E.g. where Python emits a `SyntaxError`, so does Hy; same for `TypeError`s.
Multiple tests have been added that check the format and type of raised
exceptions over varying command-line invocations (e.g. interactive and not).
A new exception type for `require` errors was added so that they can be treated
like normal run-time errors and not compiler errors.
The Hy REPL has been further refactored to better match the class-structured
API. Now, different error types are handled separately and leverage more base
class-provided functionality.
Closeshylang/hy#1486.
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.
This version is much simpler.
At the point that the exception is raised, we don't have access to
the actual source, just the current expression. but as the
exception percolates up, we can intercept it, add the source and
the re-raise it.
Then at the final point, in the cmdline handler, we can choose to
let the entire traceback print, or just the simpler, direct error
message.
And even with the full traceback, the last bit is nicely formatted
just like the shorter, simpler message.
The error message is colored if clint is installed, but to avoid
yet another dependency, you get monochrome without clint.
I'm sure there is a better way to do the markup, the current method
is kludgy but works.
I wish there was more shared code between HyTypeError and LexException
but they are kind of different in some fundamental ways.
This doesn't work (yet) with runtime errors generated from Python,
like NameError, but I have a method that can catch NameError and turn it
into a more pleasing output.
Finally, there is no obvious way to raise HyTypeError from pure Hy code,
so methods in core/language.hy throw ugly TypeError/ValueError.
