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From the IDE point of view, there are other benefits besides correctness. Proper autocomplete for objects (huge whenever you have a chain of method calls), ctrl

From the IDE point of view, there are other benefits besides correctness. Proper autocomplete for objects (huge whenever you have a chain of method calls), ctrl+click to go to a method, showing a method's documentation in a popup, find usages - all these require the IDE to know about types if they are to work reliably.

DasIch 11y ago
No, they aren't. In order to make use of type hints for anything, they need to be correct. If they aren't, anything else you build on top of them will be unreliable and confusing. As long as there is no way to check them, they're worthless.
- realharo 11y ago
  If a library comes annotated with types, then an error in the typehints is just as much of a bug as an error in code or documentation. Having most of the standard library plus large portions of the ecosystem come with these hints will be hugely beneficial for productivity. And of course, there IS a way to check them. IDEs, linters, etc. - I'm sure if you say that your function returns an instance of User and then you try to return a boolean, they will yell at you. And I expect that the standard library and popular libraries WILL run these tools before releasing a stable version. A 90% percent solution is still a step forward compared to relying on much less reliable human brains at every step.
  - DasIch 11y ago
    I understand that errors in type hints are bugs just like errors in code are. That's the problem. The entire point of type systems is to enforce correctness. They allow you to describe problems on the type level and ensure that the code being described matches that description, eliminating certain classes of bugs. That's why languages have them, that's the expectation. Type hints are just an overhyped standardized comment format with special syntax support.
    - realharo 11y ago
      I agree that type hints are basically just "machine-readable documentation" (and human-readable as well!). I still think that machine-readable documentation can be immensely useful when combined with a static code analysis tool. Not as useful as "real" static types would be, but useful nonetheless. It is the exact same idea as Microsoft's SAL annotations for C/C++ - https://msdn.microsoft.com/en-us/library/ms182032.aspx https://msdn.microsoft.com/en-us/library/ms182032.aspx, or Java's @NonNull, @ReadOnly, etc. annotations.

DasIch 11y ago

No, they aren't. In order to make use of type hints for anything, they need to be correct. If they aren't, anything else you build on top of them will be unreliable and confusing. As long as there is no way to check them, they're worthless.

realharo 11y ago
If a library comes annotated with types, then an error in the typehints is just as much of a bug as an error in code or documentation. Having most of the standard library plus large portions of the ecosystem come with these hints will be hugely beneficial for productivity. And of course, there IS a way to check them. IDEs, linters, etc. - I'm sure if you say that your function returns an instance of User and then you try to return a boolean, they will yell at you. And I expect that the standard library and popular libraries WILL run these tools before releasing a stable version. A 90% percent solution is still a step forward compared to relying on much less reliable human brains at every step.
- DasIch 11y ago
  I understand that errors in type hints are bugs just like errors in code are. That's the problem. The entire point of type systems is to enforce correctness. They allow you to describe problems on the type level and ensure that the code being described matches that description, eliminating certain classes of bugs. That's why languages have them, that's the expectation. Type hints are just an overhyped standardized comment format with special syntax support.
  - realharo 11y ago
    I agree that type hints are basically just "machine-readable documentation" (and human-readable as well!). I still think that machine-readable documentation can be immensely useful when combined with a static code analysis tool. Not as useful as "real" static types would be, but useful nonetheless. It is the exact same idea as Microsoft's SAL annotations for C/C++ - https://msdn.microsoft.com/en-us/library/ms182032.aspx https://msdn.microsoft.com/en-us/library/ms182032.aspx, or Java's @NonNull, @ReadOnly, etc. annotations.