package main

import (
    "fmt"
    "gopkg.in/yaml.v2"
)

var body = `
foo: &foo
  some: "var"

bar:
  <<: *foo
`

type Foobar struct {
    Foo interface{}
    Bar interface{}
}

func main() {
    // works as expected
    f := &Foobar{}
    if err := yaml.Unmarshal([]byte(body), &f); err != nil {
        fmt.Println(err)
    }
    fmt.Printf("%+v\n", f) // &{Foo:map[some:var] Bar:map[some:var]}

    // fails parsing yaml inheritance
    f1 := &yaml.MapSlice{}
    if err := yaml.Unmarshal([]byte(body), &f1); err != nil {
        fmt.Println(err)
    }
    fmt.Printf("%+v\n", f1) // &[{Key:foo Value:[{Key:some Value:var}]} {Key:bar Value:[]}]
    // expected: &[{Key:foo Value:[{Key:some Value:var}]} {Key:bar Value:[{Key:some Value:var}]}]
}