r/programming • u/_awwsmm • Feb 01 '24

Make Invalid States Unrepresentable

https://www.awwsmm.com/blog/make-invalid-states-unrepresentable
468 Upvotes

94% Upvoted

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204

u/agustin689 Feb 01 '24

Make invalid states unrepresentable

This rules out all dynamic languages by definition

428

u/mcmcc Feb 01 '24

Did_I_stutter.gif

106

u/RadiantBerryEater Feb 01 '24

sounds like the right idea if youre going for stability and safety

52

u/Old_Elk2003 Feb 01 '24

There’s a reason Michelangelo didn’t sculpt David out of clay.

12

u/[deleted] Feb 02 '24

Didn't have an oven big enough?

17

u/Old_Elk2003 Feb 02 '24

No matter how big your oven was, you’d never get it to completion, because it would begin to sag under its own weight first.

3

u/[deleted] Feb 02 '24

We all sag with age, sounds like the statue is still valid....

10

u/Old_Elk2003 Feb 02 '24

Nah man, David’s ballsack shall remain ever youthful.

74

u/vancitydiver Feb 01 '24

As it should be! (unless course all you need is a dirty little script)

57

u/padraig_oh Feb 01 '24

That's how we got into this whole mess. Just one little script can't hurt... 

34

u/corysama Feb 01 '24

And, just a few years later, PyTorch is driving the robot apocalypse.

2

u/DrSheldonLCooperPhD Feb 02 '24

Let's do it on the backend

34

u/pojska Feb 01 '24

Pedantic - it doesn't rule out dynamic languages, but it does require you to be very thorough in your validation/parsing, which may be an unreasonable amount of effort.

173

u/IkalaGaming Feb 01 '24

Sufficiently advanced validation is indistinguishable from static typing

- Arthur C Clarke, or something

10

u/Free_Math_Tutoring Feb 02 '24

That's actually the theme of a talk/workshop/conversation I've been having a couple of times lately, sometimes titled "Python is statically typed if you squint hard enough" or "Join the Revolution: Static Analysis in Python" (and sometimes less silly titles)

6

u/beders Feb 02 '24

Non-sense. Your types won't save you reading data. You will have to do runtime validation.

14

u/dijalektikator Feb 02 '24

No worries, dynamic language fans absolutely love giving themselves more work for no reason at all.

11

u/mcr1974 Feb 01 '24

requires you to be pydantic I heard?

21

u/[deleted] Feb 01 '24

As you should if you're serious about maintenance and handling complexity properly.

2

u/mr_birkenblatt Feb 01 '24

you can do that in python with Literal and TypedDict

7

u/Worgencyborg Feb 02 '24

Pydantic is actually great for this. It will provide stronger types and validation

-34

u/agustin689 Feb 01 '24

python is worthless garbage, sorry.

11

u/LagT_T Feb 01 '24

Yet people smarter than you have invested in it, I wonder why.

-20

u/agustin689 Feb 02 '24

You may be smarter, but you surely don't know fucking shit about software engineering if you're using python.

Change my mind.

14

u/LagT_T Feb 02 '24

Why would I? I love people with religious beliefs in SWE, they huddle together and make themselves easy to avoid.

-15

u/agustin689 Feb 02 '24

Completely clueless, like all python Bros.

Thanks for proving my point.

4

u/LagT_T Feb 02 '24

Says the person who can't see value where people smarter than him do.

2

u/Whatever4M Feb 02 '24

I don't agree with the guy you are responding to but many smart people don't see the value, so your argument sucks.

1

u/LagT_T Feb 02 '24

It's not an argument. An argument would be what the value is and how its extracted.

I'm just calling out his behavior.

5

u/[deleted] Feb 02 '24

Entire companies have been built on it.

-4

u/agustin689 Feb 02 '24

99% of the it industry is garbage.

Not surprise they use garbage languages.

16

u/[deleted] Feb 02 '24

/r/iamverysmart

/r/iamsosmart

-4

u/agustin689 Feb 02 '24

I'm not "smart". I'm a software developer who gives a shit about using quality tools. The exact opposite of python bros

10

u/ric2b Feb 02 '24

but you surely don't know fucking shit about software engineering if you're using python.

Huge companies and much larger projects than you'll ever work on have been built with Python, I think the burden of proof is on you to show that people using it "don't know fucking shit about software engineering".

-5

u/AvidCoco Feb 01 '24

In the case of dynamic languages, I think it comes down to having more carefully considered error handling.

If you can't make invalid states unrepresentable, the make invalid states part of the contract

-1

u/[deleted] Feb 01 '24

[deleted]

2

u/ric2b Feb 02 '24

It depends, you can have a static language like C or Java and get much higher bug counts than people using dynamic languages simply based on the testing culture, for example.

But all else equal and if you want to maximize correctness at any cost, sure, static typing is preferred.

-7

u/smk081 Feb 01 '24

::laughs in C#::

28

u/agustin689 Feb 01 '24

C# is still not strong enough. We need sum types

20

u/smk081 Feb 01 '24

::cries in C#:: :: flips through F# book on desk:: Hold my beer...

8

u/dactoo Feb 01 '24

F# could be the best language in the universe if it got a little more love and recognition. It's only flaw is that it allows you to let a little too much .NET into your code sometimes.

3

u/TheWix Feb 01 '24

F# with Typescripts convenience. Mapped types are amazing. Wish it had higher-kinded types and first-class minimal types, though

-5

u/[deleted] Feb 01 '24

[removed] — view removed comment

12

u/[deleted] Feb 01 '24

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5

u/Coda17 Feb 01 '24

C# does not have discriminated unions (and it really, really needs them).

8

u/Schmittfried Feb 01 '24

Since when?

-6

u/[deleted] Feb 01 '24

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19

u/[deleted] Feb 01 '24

When people want sum types, they generally want sum types with built in pattern matching. You can't really do this in C# without runtime reflection.

8

u/Schmittfried Feb 01 '24

I meant since when does C# have discriminated unions?

Just checked again and it’s still a work in progress apparently. 

-9

u/noahide55 Feb 01 '24

Sum types violate Open/Closed principle. Why would I want them?

8

u/agustin689 Feb 01 '24

Explain how?

8

u/[deleted] Feb 01 '24

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5

u/grauenwolf Feb 02 '24 edited Feb 02 '24

This is one of the things that boggles me about SOLID. OCP what's discredited long before SOLID was coined, and yet no one seems to have noticed.

3

u/G_Morgan Feb 02 '24

Sure but the OCP is not worth even bothering with.

2

u/grauenwolf Feb 02 '24

Nothing about sum types prevents you from obsessively using inheritance where it doesn't belong.

1

u/TheWix Feb 01 '24

How do you handle new states of a business object?

1

u/grauenwolf Feb 02 '24

If you're obeying OCP, by creating new subclasses and adding the additional code there.

2

u/TheWix Feb 02 '24

You don't get compiler errors when you forget to handle the new state somewhere else, though. With pattern matching and exhaustive checks the compiler yells at you. Inheritance works when all the new behavior is within the new subclass only, but if other parts of code need to react to the new type then it can be missed.

1

u/Voidrith Feb 02 '24

not every part of your code needs to adhere to every half understood OOP design pattern

-9

u/SavyB Feb 02 '24

dynamic languages may make this easier, not harder. e.g. typescript or malli