#+title: Oil shell
#+date: "2021-05-09 16:40:50 +08:00"
#+date_modified: "2021-05-09 17:15:03 +08:00"
#+language: en


For future references:

#+begin_src sh  :results output
oil --version
#+end_src

#+RESULTS:
: Oil version 0.8.7
: Release Date: 2021-01-23 07:35:11+00:00
: Arch: x86_64
: OS: Linux
: Platform: #13~1617215757~20.10~97a8d1a-Ubuntu SMP Thu Apr 1 21:09:17 UTC 2
: Compiler: GCC 10.2.0
: Interpreter: OVM
: Interpreter version: 2.7.13
: Bytecode: bytecode-opy.zip

This version contains incomplete implementation and documentation which is why I'm noting it here.

- You can make an array so far with ~var x = %()~.

- To push for an array, use ~push :ARRAY_VAR $ITEMS...~.

- Oil has two main syntactic modes: command and expression mode.
  Command mode is more like Bash while expression mode is more like Python.
  This is how Oil can make a rich and expressive scripting that is closer to the shell.

- Oil will go into expression mode in few places:
  + In RHS of an assignment expression.
  + In ~if~ statements (e.g., ~if ($EXPR) { echo "WHOA" }~).
  + Interpolated Oil expressions with ~$[]~ (e.g., ~$[true]~, ~$[len(ARGV)~).

- Oil can parse different modes, making it possible to create DSLs and to deal with the complex syntax of the shell.

- You can also create an array with ~[]~.
  The ~%()~ is more like for an array of objects.

- You can enter into expression mode with ~_~.
  Although, this simply ignores the expression and will not be printed.
  Still pretty useful.