notes
-----

- add tests
  . test all existing behavior
  . add parsing tests
  . check dependency ordering

- allow leading tabs or leading spaces, but not a mix
  after leading tabs, additional spaces or tabs are allowed
  for line continuation
  after leading spaces, only additional spaces are allowed
  for line continuation

- parsing tests
  . --list: make sure the right dependencies are listed
  . --show: make sure the recipe contents is parsed

make sure that bad names are disallowed
trigger all errors

- look through all justfiles for features of make that I use. so far:
  . phony
  . SHELL := zsh
  . quiet
  . make variables

- ask travis for his justfile


- remove make dependency
  . recipes must be '[a-z][a-z0-9-]*'
  . only allow tabs or spaces, but not both in a recipe
  . simple, but with recipe dependencies
  . increased indentation for line continuations
  . be as strict as possible, to make future additions
    backwords compatible

- add optional shebangs to recipes
  . extract and run script
  . preserve line numbers
  . pass args as real args

- ~/.justfile
  . is this for non-project specific commands, so that when you
    type .j in any directory, it uses it as a justfile?
  . or is it for commands which are useful across projects?

- allow a top-level shebang to script in whatever language
  you like. all recipes are now implicitly in that language
  . extract script up until --
  . this may be ill-advised
  . how do i deal with running the prelude multiple times?
  . multiple top level shebangs?
    #!/usr/bin/env python3
    ... python prelude
    ---
    python-recipe:
      print("hello")
    #!/usr/bin/env perl
    ... perl prelude
    ---
    perl-recipe:
      print "hello"

- what is the story for allowing justfiles in subdirectories?
  use a different name, like 'subjustfile' or 'jfile'.
  recurse up to the justfile, but add recipes in any jfile
  that you find along the way. recipes in justfile are accessible,
  and run from the justfile dir. recipes in jfile are run from jfile
  dir. refuse to run if a recipe in justfile and jfile conflict

- add a command for fanning out?
  `j --all build` fans out into subdirectories and builds

- rust is a given, so one option is to write a very simple shell
  language and only call binaries from cargo. include some kind
  of dependency description, and install those binaries. should
  look at rc for inspiration. 'cargo cult' is a great name.
  perhaps it could avoid barewords, and actually have types that
  map to rust types.

- mascot?
  . tower of babel
  . howl's moving castle
  . testuo
  . thoth
  . kali

- would it be useful to expose original directory to j recipes?

- comedy option: super complex recipe lines:
  a: b c # run b and c, then a
  b | a: c # run c, then b, and pipe output of b into a
  a >> a.log: # run a and append output to a.log
  a B C: # a takes B and C as command line args, like j a HELLO BOB
         # can enforce at command line