是否有惯用的Go方法来烘干以下代码：

I seem to be repeating the speak function for example.

Also is there a way to move the initial knowledge of the baby and the human to a default constructor instead of being passed while making a new baby and human?

package main

import (
    "fmt"
)

func main() {
    h := Human{"good things"}
    d := Devil{}
    b := Baby{"ga ga"}
    b.speak()
    h.speak()
    d.poisons(&h)
    d.poisons(&b)
    b.speak()
    h.speak()
}

type Human struct {
    Knowledge string
}

type Devil struct{}

type Baby struct {
    Knowledge string
}

type Knowledgable interface {
    changeKnowledge(newKnowledge string)
}

func (d Devil) poisons(creature Knowledgable) {
    creature.changeKnowledge(" evil things")
}

func (h Human) speak() {
    fmt.Println(h.Knowledge)
}

func (b Baby) speak() {
    fmt.Println(b.Knowledge)
}

func (h *Human) changeKnowledge(newKnowledge string) {
    h.Knowledge += newKnowledge
}

func (b *Baby) changeKnowledge(newKnowledge string) {
    b.Knowledge = newKnowledge
}

About speak() function you can embed

type Knowledge string
func (b Knowledge) speak() {
    fmt.Println(b)
}
type Baby struct {
    Knowledge
}
type Human struct {
    Knowledge
}

and about constructors, seems for such a simple type buitin new() is OK but you can write an initializer

func Ini(k Knowledgable) {
    switch k.(type) {
    case *Baby:
        k.changeKnowledge("ga-ga")
    case *Human:
        k.changeKnowledge("good things")
    }
}

then things will be

h := new(Human)
b:=new(Baby)
Ini(h)
Ini(b)
h.speak()

if I didn't misunderstand, you want to make a "constructor" for the Baby and Human. There are some equivalents of constructors in Go.

If you have the Human struct:

type Human struct {
    Knowledge string
}

You can call a function makeHuman to create a new Human:

func makeHuman(knowledge string) Human {
    return Human{knowledge}
}

If you prefer to return a pointer, you can choose this one:

func newHuman(knowledge string) *Human {
    return &Human{knowledge}
}

You can check both options in the links below: