## Functionality

 - [x] And or lists
 - [ ] Pipelines
   - [x] Simple
       - Better structured concurrency handling, will eventually need a notion
         of background/global Eio.Switch.t.
   - [ ] Redirections
     - [x] Simple input/output redirects
     - [x] More complicated FD dupping ones (e.g. `>&3`)
     - [ ] Clobbering
     - [ ] `<>` support
 - [ ] Loops
   - [ ] For loops
   - [ ] While/Until loops
 - [ ] Conditionals
 - [ ] Substitutions
   - [ ] Globs
 - [ ] Traps
 - [ ] Background Tasks
 - [ ] Interactive Mode
   - [x] Initial prototype
   - [ ] Signals (e.g. ctrl+D)
 - [ ] Built-ins
   - [x] Basic cmdliner infrastructure  
   - [ ] cd
     - [x] Basic functionality
     - [ ] Flags
   - [ ] pwd
     - [x] Basic functionality
     - [ ] Flags
   - [ ] which

## Conformance Testing