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On 10.09.2015 06:12, Jukka Lehtosalo wrote:<br>
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<div class="gmail_quote">This has been discussed almost to the
death before, <br>
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I am sorry. :)<br>
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<div>but there are some of main the benefits as I see them:</div>
<div>- Code becomes more readable. This is especially true
for code that doesn't have very detailed docstrings.</div>
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If I have code without docstrings, I better write docstrings then.
;)<br>
<br>
I mean when I am really going to touch that file to improve
documentation (which annotations are a piece of), I am going to add
more information for the reader of my API and that mostly will be
describing the behavior of the API.<br>
<br>
If my variables have crappy names, so I need to add type hints to
them, well, then, I rather fix them first.<br>
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<div>This may go against the intuition of some people, but
my experience strongly suggests this, and many others
who've used optional typing have shared the sentiment. It
probably takes a couple of days before you get used to the
type annotations, after which they likely won't distract
you any more but will actually improve code understanding
by providing important contextual information that is
often difficult to infer otherwise.</div>
<div>- Tools can automatically find most (simple) bugs of
certain common kinds in statically typed code. A lot of
production code has way below 100% test coverage, so this
can save many manual testing iterations and help avoid
breaking stuff in production due to stupid mistakes (that
humans are bad at spotting).</div>
<div>- Refactoring becomes way less scary, especially if you
don't have close to 100% test coverage. A type checker can
find many mistakes that are commonly introduced when
refactoring code.</div>
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<div>You'll get the biggest benefits if you are working on a
large code base mostly written by other people with
limited test coverage and little comments or
documentation.</div>
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If I had large untested and undocumented code base (well I actually
have), then static type checking would be ONE tool to find out
issues.<br>
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Once found out, I write tests as hell. Tests, tests, tests. I would
not add type annotations. I need tested functionality not proper
typing.<br>
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<div>You get extra credit if your tests are slow to run and
flaky,</div>
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We are problem solvers. So, I would tell my team: "make them faster
and more reliable".<br>
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<div class="gmail_quote">I consider that difference pretty
significant. I wouldn't want to increase the fraction of
unchecked parts of my annotated code by a factor of 8, and I
want to have control over which parts can be type checked.</div>
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Granted. But you still don't know if your code runs correctly. You
are better off with tests. And I agree type checking is 1 test to
perform (out of 10K).<br>
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But:<br>
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I don't see the effort for adding type hints AND the
effort for further parsing (by human eyes) justified by
partially better IDE support and 1 single additional
test within test suites of about 10,000s of tests.<br>
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Especially, when considering that correct types don't
prove functionality in any case. But tested
functionality in some way proves correct typing.<br>
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<br>
I didn't see you respond to that. But you probably know that. :)<br>
<br>
Thanks for responding anyway. It is helpful to see your intentions,
though I don't agree with it 100%.<br>
<br>
Moreover, I think it is about time to talk about this. If it were
not you, somebody else would finally have added type hints to
Python. Keep up the good work. +1<br>
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Best,<br>
Sven<br>
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