Command line tools to generate a fast and human readable diff::

$ cat a.yml
a: hello
b: world
d:
    a: a
    b: b
    A: A
$ cat b.yml
a: world
c: hello
d:
    a: a
    b: b
    c: c
$ yamlkeysdiff a.yml b.yml
> b
< c
> d:A
< d:c
$ yamlkeysdiff "a.yml#d" "b.yml#d"
> A
< c

You can install it from hackage::

$ cabal update
$ cabal install yamlkeysdiff

::

$ cabal sandbox init  # Always use sandboxes (like python virtual env)
$ cabal install --only-dependencies  # Install the package dependencies
# if this fails, try:
# cabal install --only-dependencies --force-reinstalls
$ cabal configure
$ cabal build
$ ./dist/build/yamlkeysdiff/yamlkeysdiff

You can also do that with::

$ make all

• Add tests
• Don't compare the subkeys when the parent key is missing
• Write a generic diff function which can diff many files