Haskell Community

Why use an effect system?

atravers November 30, 2024, 11:39pm 82

You mean the RealWorld mentioned here?

```
data State# a :: ZeroBitType
```
State# is the primitive, unlifted type of states. It has one type parameter, thus State# RealWorld, or State# s, where s is a type variable. The only purpose of the type parameter is to keep different state threads separate. It is represented by nothing at all.

GHC.Prim (State#)
```
type ZeroBitType = TYPE ZeroBitRep
```
The kind of the empty unboxed tuple type (# #)

GHC.Types (ZeroBitType)
```
type Void# = (# #)
```
Deprecated: Void# is now an alias for the unboxed tuple (# #)

GHC.Types (Void#)

…how exactly should that be explained to future beginners?