[Python-ideas] allow `lambda' to be spelled λ

Chris Angelico rosuav at gmail.com
Tue Jul 19 11:13:13 EDT 2016

On Wed, Jul 20, 2016 at 1:03 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> The reason that can help is that the main problem with "improving"
> error messages, is that it can be really hard to tell whether the
> improvements are actually improvements or not (in some cases it's
> obvious, but in others it's hard to decide when you've reached a point
> of "good enough", so you throw up your hands and say "Eh, it's at
> least distinctive enough that people will be able to find it on Stack
> Overflow").

Plus, there are all sorts of errors that look very different to
humans, but identical to the parser. Steven showed us an example where
an invalid character looked like it belonged in the identifier, yet to
the parser it's just "this Unicode category isn't valid here", same as
the bad-quote one. In a *very* few situations, a single error is
common enough to be worth special-casing (eg print without
parentheses, in recent Pythons), but otherwise, Stack Overflow or
python-list will do a far better job of diagnosis than the lexer ever
can. Ultimately, syntax errors represent an error in translation from
a human's concept to the text that's given to the interpreter, and
trying to reconstruct the concept from the errant text is better done
by a human than a computer. Obviously it's great when the computer can
read your mind, but it's never going to be perfect.


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