Tiny App Tutorial: Todo CLI

In this tutorial we’ll build a tiny Todo CLI in SUP that supports adding, listing, and completing items.

Prerequisites

• Install SUP: pip install sup-lang

Project setup

Create todo.sup:

sup
  note Initialize an empty list (grammar requires at least one item)
  make list of 0
  set todos to the list
  pop from todos

  define function called add with text
    push text to todos
    print concat of "Added: " and text
  end function

  define function called list
    for each item in todos
      print item
    end for
  end function

  define function called done with index
    note convert 1-based to 0-based
    set n to subtract 1 from index
    print concat of "Done: " and get n from todos
  end function

  # Simple router using args
  set cmd to args get of 0
  if cmd is equal to "add" then
    set text to args get of 1
    call add with text
  else if cmd is equal to "list" then
    call list
  else if cmd is equal to "done" then
    set idx to args get of 1
    call done with idx
  else
    print "Usage: sup todo.sup [add TEXT|list|done INDEX]"
  end if
bye

Run

sup todo.sup add "buy milk"
sup todo.sup add "write code"
sup todo.sup list
sup todo.sup done 1

Going further

• Persist to disk: use write file of PATH and DATA and read file of PATH with json stringify/parse.
• Packaging: transpile to Python and wrap with a launcher script.