Monoid examples
We'll cover three types of monoid here:
- Name monoid
- Int slice monoid
- Line item monoid
That's right. We're going to turn that invoice into a monoid!
Name monoid
Let's see what we can do with a name. First, we define an interface that has two methods, Append and Zero. We wrap our name in nameContainer.
Our nameContainer is a struct with a single string field, name. Our Append method appends the given name to the long name string it's building up that lives in the magical nameContainer. Our zero morphism for our name string is an empty string.
The content of src/monoid/name_monoid.go would look as follows:
package monoid
type NameMonoid interface {
Append(s string) NameMonoid
Zero() string
}
func WrapName(s string) NameMonoid {
return nameContainer{name: s}
}
type nameContainer struct {
name string
}
func (s nameContainer) Append(name string) NameMonoid {
s.name = s.name + name
return s
}
func (nameContainer) Zero() string {
return ""
}
func (s nameContainer) String...
