this post was submitted on 09 Feb 2024
89 points (100.0% liked)
Programming
17334 readers
313 users here now
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
- Follow the programming.dev instance rules
- Keep content related to programming in some way
- If you're posting long videos try to add in some form of tldr for those who don't want to watch videos
Wormhole
Follow the wormhole through a path of communities !webdev@programming.dev
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
So the core concept is that when you validate some property about input you should also transform the input into a new form that represents the new guarantee in the type system.
This is very, closely related to the "make invalid states unrepresentable" concept. If we have validated our list to be non empty, we should return a non empty list - after all an empty list is now invalid and as such the type system should exclude that possibility.
Yes! The concepts are intertwined. I think the key take away, for me, is to lean heavily into your type system and allow that to do some of the heavy lifting. Accept that something like a
usernameis not a string, but a subtype of a string (this has to be true if any validation is required, otherwise you'd just accept any valid string).