Terminal

Elixir Terminal UIs with Reactish API

Uses teletype for native TTY support

Demo

#from bash (no logs)
#Ctrl+c to exit
mix run exs/demo.exs

Development

# socat file:/dev/tty,raw,icanon=0,echo=0,min=0,escape=0x03 tcp-l:8880,reuseaddr
# socat STDIO fails with: Inappropriate ioctl for device
# no resize event is received with this method
# raw required to avoid translating \r to \n
# min=0 required to answer size query immediatelly
# fork useless because term won't answer size query on reconnection
# escape=0x03 required to honor escape sequences (ctrl-c)
# while true; do socat file:/dev/tty,raw,icanon=0,echo=0,min=0 tcp-l:8880,reuseaddr; done
# while true; do socat file:/dev/tty,raw,icanon=0,echo=0,min=0,escape=0x03 tcp-l:8880,reuseaddr; done
# to exit: ctrl-z, then jobs, then kill %1
#
# socat file:/dev/tty,nonblock,raw,icanon=0,echo=0,min=0,escape=0x03 tcp:127.0.0.1:8880
# client socat to test immediate transmission of typed keys on both ends
# escape=0x03 reqired to honor ctrl-c
#
# echo -en "\033[1mThis is bold text.\033[0m" | nc 127.0.0.1 8880
# to test server end honors escapes
mix run exs/demo.exs --socat
#_build/dev/lib/teletype/priv/ptm
mix run exs/demo.exs --ptm

Design

• Only tested so far on VS Code integrated terminal and Linux legacy TTY.
• Very minimal escape sequences to ensure Linux TTY works.
• Control event handlers triggered only from keyboard events
• Use react state and control events instead of getters (on_change instead of get_value)
  • Corollary: Controls are not focusable if on_handler is nil
• Function components external children must be ignored
• No mixing on logic and markup allowed. State and logic to the top, markup to the bottom.
• Null effects may be executed multiple times in a single user event because of state changes propagation.
• The reason for use_effect (instead of direct execution from event handlers) is its cleanup mechanism.
• Effects and cleanups are executed post render in same render process.
• Mouse wheel may focus but not trigger constrol actions.
• Select and Radio items can be any datatype implementing String.Chars.
• Exceptions in timeout/interval handlers should kill the application.
• Cleanups should be idempotent.
• Enter should navigate to next control for all controls except buttons.
• Dialog buttons order should be accept then cancel to take advange of enter navigation.
• Escape should close dialogs from any current focused control (shortcut).
• No matter the effort dirty exits are innevitable.

Issues

• konsole is not consistently responding size queries as vscode term does

Future

• Ctrl-c cancel
• Ctrl-c cleanup
• Ctrl-c handler
• Resize handler
• XTerm support
• Konsole support
• MacOS terminal support
• Explicit screen redraw
• TextArea
• Drag and drop
• Selection
• Clipboard
• Input scrolling
• Cursor pos after SIGWINCH/size-query
• Input validation
• Mouse
• Mouse wheel
• Modals
• Checkbox
• Reversed tab
• Commands
• Subscriptions
• Term behaviour
• Zero index coordinates
• Tab index testing
• Tab navigation testing
• Arror up/down navigation
• List rendering
• Nil rendering
• Keyboard shortcuts
• Modal accept/cancel
• Conditional rendering
• Use effect execution order
• Use effect cleanups
• Timer API
• Test refocus
• Test reverse nav
• Test canvas && diffing
• Test visible propagation
• Kill app with ctrl+c