What's the best way to minimize the need of run time checks?

[Juan Pablo Romero Méndez]

What static checking can actually guarantee varies depending on the
specific type system at hand (C# vs Haskell vs Idris for example). But most
of them can guarantee simple stuff like: "I'm I allowed to invoke this
function at this point?"

If you don't have that, well you can rely on tests to show that certain
code paths behave in a certain way when exercised with certain inputs.



2016-08-09 12:22 GMT-07:00 MRAB <python at mrabarnett.plus.com>:

> On 2016-08-09 19:57, Chris Angelico wrote:
>
>> On Wed, Aug 10, 2016 at 4:51 AM, Michael Selik <michael.selik at gmail.com>
>> wrote:
>>
>>> "File-like" is a good example. Rather than go through the frustration of
>>> a
>>> formal definition for what is file-like, stay productive and flexible
>>> with
>>> duck typing. Objects that don't have the appropriate methods or
>>> attributes
>>> will cause a TypeError or AttributeError. If you're passing in the wrong
>>> kind of object, you'll find out almost as soon as you write the code
>>> (because you test early and often), just as you would with a statically
>>> analyzed type system.
>>>
>>
>> It's slightly delayed; with Python, you have to actually execute the
>> code path in question, whereas a static type system would detect it at
>> the compilation stage. So it may depend on the quality of your
>> testing. MyPy may be able to help there.
>>
>> Static checking won't tell you if, say, you're adding when you should be
> subtracting, so you'd need to execute the code path in question anyway
> during testing!
>
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