Keep your Types Small
Why?
(the size of a type is how many values (terms) it can hold (inhabit it).
The less terms can inhabit a running instance of your codebase; the less bugs and surprise you are likely to find.
Why?
enum MarkerColor:
case Red
case Green
case Bluehas fewer surprises than
type MarkerColor = IntWhy?
The State Space of your codebase relates to Entropy and is the biodiversity index of bugs living in it.
But there is a surprising impact on a couple of small things you can do...
https://medium.com/swlh/type-system-saving-55db2ca062ff
Recap
(the size of a type is how many values (terms) it can hold (inhabit it).
• Nothing has 0 terms
• Unit has 1 term
• Boolean has 2
• Byte has 256
What's the size of a type?
Recap
You can combine different types os the number of terms they can hold can be:
- added (enums, Either)
- multiplied (tuples, case classes)
- exponentiated (maps, functions)
- and more...
What's the size of a type?
enum Three:
case One
case Two(b: Boolean)case class Four(two: Boolean, too: Boolean)type Pow[Base, Exponent] = Map[Exponent, Base]
type Eight = Pow[Two, Three]https://alexknvl.com/posts/counting-type-inhabitants.html
Actions:
Start with your domain model.
Actions:
Make your functions generic.
Actions:
Identify algebras in your code.
Connections
References
- https://medium.com/swlh/type-system-saving-55db2ca062ff
- https://alexknvl.com/posts/counting-type-inhabitants.html
- https://github.com/cohomolo-gy/Type-Arithmetic-and-the-Yoneda-Perspective
- https://bartoszmilewski.com/2014/09/22/parametricity-money-for-nothing-and-theorems-for-free/
- https://github.com/Constructive-Programming/scala-cardinality