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The benefits of static typing without static typing in Python

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Re: The benefits of static typing without static typing in Python

#11

Post by zeckalpha »

ptype wrote: post #9
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I hear this argument a lot, and I'm sure static typing is helpful when refactoring, but I have found that nothing is as important as tests when refactoring. I'd rather refactor dynamically typed code with good test coverage than statically typed code without good tests.

It is better with certain languages, and it is better when you encode business logic into your type system.

Re: The benefits of static typing without static typing in Python

#12

Post by JustSomeNobody »

japhyr wrote: post #7
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I haven't done large-scale refactoring work before. How does typing help with refactoring? Is it because you know exactly what's being passed into a function?

Or that they're just used to their IDE doing all of it for them.

Re: The benefits of static typing without static typing in Python

#13

Post by incepted »

ptype wrote: post #9
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I hear this argument a lot, and I'm sure static typing is helpful when refactoring, but I have found that nothing is as important as tests when refactoring. I'd rather refactor dynamically typed code with good test coverage than statically typed code without good tests.

> but I have found that nothing is as important as tests when refactoring

You don't need those with static types. You only need to write tests for your actual code, not things that the compiler can check for you.

Manually writing code to check things the computer can test for you is a waste of developers time.

Re: The benefits of static typing without static typing in Python

#14

Post by incepted »

japhyr wrote: post #7
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I haven't done large-scale refactoring work before. How does typing help with refactoring? Is it because you know exactly what's being passed into a function?

You missed "automated" in "automated refactorings". This is what I'm talking about.

Without types, IDE's can't perform automated refactorings: you need to supervise them and make sure the IDE didn't break code.

This can't happen with static types.

Re: The benefits of static typing without static typing in Python

#15

Post by luos »

japhyr wrote: post #7
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I haven't done large-scale refactoring work before. How does typing help with refactoring? Is it because you know exactly what's being passed into a function?

It really helps when renaming methods for example. I am not sure how much it helps with extract method.

Re: The benefits of static typing without static typing in Python

#16

Post by DougBTX »

japhyr wrote: post #7
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I haven't done large-scale refactoring work before. How does typing help with refactoring? Is it because you know exactly what's being passed into a function?

Typing makes it easier to write a "find all references" function. Types distinguish whether a call to foo.bar() is calling the same bar as baz.bar(), which makes it easier to rename Foo's bar wherever it is used, but leave Baz's bar alone.

Re: The benefits of static typing without static typing in Python

#17

Post by yrro »

incepted wrote: post #13
ptype wrote: post #9

Earlier quoted context omitted.

I hear this argument a lot, and I'm sure static typing is helpful when refactoring, but I have found that nothing is as important as tests when refactoring. I'd rather refactor dynamically typed code with good test coverage than statically typed code without good tests.

> but I have found that nothing is as important as tests when refactoring You don't need those with static types. You only need to write tests for your actual code, not things that the compiler can check for you. Manually writing code to check things the computer can test for you is a waste of developers time.

The type system only goes so far. If your refactored code calls functions that take several different parameters of the same type, you can make mistakes that the compiler won't catch.

Re: The benefits of static typing without static typing in Python

#18

Post by montibbalt »

incepted wrote: post #14
japhyr wrote: post #7

Earlier quoted context omitted.

I haven't done large-scale refactoring work before. How does typing help with refactoring? Is it because you know exactly what's being passed into a function?

You missed "automated" in "automated refactorings". This is what I'm talking about. Without types, IDE's can't perform automated refactorings: you need to supervise them and make sure the IDE didn't break code. This can't happen with static types.

It makes manual refactoring easier too in the sense that you now have a tool that can tell you what you broke and how to fix it.

Re: The benefits of static typing without static typing in Python

#19

Post by geofft »

ptype wrote: post #9
incepted wrote: post #4

The main advantage of static typing to me is that it enables automatic refactorings. Without types, it's impossible for tools to refactor your code safely without the supervision of a human. This leads to developers being afraid of refactoring and, ultimately, code bases rot and become huge piles of spaghetti that nobody wants to touch. With a statically typed language, I'm never afraid to refactor whenever I see an…

I hear this argument a lot, and I'm sure static typing is helpful when refactoring, but I have found that nothing is as important as tests when refactoring. I'd rather refactor dynamically typed code with good test coverage than statically typed code without good tests.

Types are tests.

In a sufficiently strong type system, you can express constraints stronger than "returns a string" or "takes an integer". For instance, if you want to make sure that a particular function always returns a valid file descriptor, make a structure for file descriptors that just contains a single int, and give it a private constructor that can only be called by the low-level functions that call the actual syscalls, or maybe a public constructor that confirms that the provided integer is actually a file descriptor. Then, as long as your function typechecks, it can only possibly return a valid file descriptor, for all possible inputs.

If you take this to an extreme, you get the https://en.wikipedia.org/wiki/Curry-Howard_correspondence, that there's a direct mapping between mathematical propositions and types, and between their proofs and functions of the corresponding type. This is what all modern proof assistants build on top of, though their type systems are usually extremely complicated.

Re: The benefits of static typing without static typing in Python

#20

Post by qwer »

Since I unit-test the heck out of my code, this doesn't really do much for me. Unit-tests test actual values (which is where the interesting bugs come from IMO) and give me more powerful refactoring capabilities than an IDE.

The real benefit I'd be looking for is the chance to give the compiler hints to speed up execution times.

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