Yaml

defaults: &anchor
  repo1: master

host:
  # Inheritance
  <<: *anchor
  repo2: branch

Summary

let indent = del /[ \t]+/ " "

the imposed indent is 2 spaces

<<: *anchor

let _repo = [ key Rx.word . colon . space . (val | mval) . eol ]

{ "repo" = "branch" }

let anchor = Util.del_str "&" . val

&anchor

let entry = [ key Rx.word . colon . (space . anchor)? . eol . (indent . comment)* . ((inherit . (repo+)?) | repo+) ]

host:
  # Inheritance
  <<: *anchor
  repo2: branch

let header = [ label "@yaml" . Util.del_str "---" . (Sep.space . store Rx.space_in)? . eol ]

let lns = ((empty|comment)* . header)? . (sequence | entry | comment | empty)*

The yaml lens

let indent = del /[ \t]+/ " "

the imposed indent is 2 spaces

let _repo = [ key Rx.word . colon . space . (val | mval) . eol ]

let anchor = Util.del_str "&" . val

let entry = [ key Rx.word . colon . (space . anchor)? . eol . (indent . comment)* . ((inherit . (repo+)?) | repo+) ]

let header = [ label "@yaml" . Util.del_str "---" . (Sep.space . store Rx.space_in)? . eol ]

let lns = ((empty|comment)* . header)? . (sequence | entry | comment | empty)*

The yaml lens