Teliva - an environment for end-user programming

“Enable all people to modify the software they use in the course of using it.” — https://futureofcoding.org/episodes/033.html

“What if we, and all computer users, could reach in and modify our favorite apps?” — https://www.inkandswitch.com/end-user-programming

“Software must be as easy to change as it is to use.” — https://malleable.systems

What's this, then?

An extremely naïve, brutalist attempt at packaging up simple Lua (5.1) apps with almost all the stuff needed to edit and build them. You will need some Unix-like platform[1] with a C compiler and the ncurses library.

Here's how you run one of the example apps (the Tower of Hanoi):

git clone https://github.com/akkartik/teliva
cd teliva
make linux
src/teliva hanoi.tlv

No matter what app you run, you are always guaranteed access to a single obvious, consistent way (currently the hotkey ctrl-e) to edit its sources. And to run the updates after editing.

[1] Tested so far on Linux and Mac OSX; should also work on BSD, WSL on Windows, etc.

Isn't this just an IDE?

There's one big difference: these apps are not intended to be runnable outside of the Teliva environment. Editing the sources will always be a core feature that's front and center in the UI.

A second, more subtle difference: it's primarily an environment for running apps, and only secondarily for editing them. Starting up the environment puts you in a running app by default. Creating an app from a clean slate is a low-priority use case, as is lots of specialized support for developing complex apps. The sweet spot for Teliva is simple apps that people will want to edit after using for a while.

Why Lua?

It's reputedly the fastest interpreted language per line of implementation code.

Will it run any Lua program?

Not quite. My priority is providing a good experience for newcomers to comprehend and modify the programs they use. If it's not clear how to provide that experience for some kinds of Lua programs, I'd rather disable support for them in Teliva and let people use regular Lua. Or other platforms!

• This approach doesn't make sense for batch programs, I think.

• I don't know how to obtain a simple, shallow graphics stack, so there's no support for graphics at the moment.

• Teliva initializes the ncurses library by default, so apps should assume they have access to a text-mode window for printing text to, and a keyboard for reading unbuffered keystrokes from.

• I want to provide sandboxed access to system resources (file system, network, etc.) which will likely create incompatibilities with the standard library. I'm disinclined to try to ‘improve’ on Lua syntax, however. It's not my favorite, but it's good enough.

Teliva is not tested much at all yet. This is my first time programming either in Lua or within Lua. So bug reports are most appreciated if Lua programs behave unexpectedly under Teliva.

Will it run any ncurses program?

Hopefully. ncurses is extremely portable; I don't test on all the configurations ncurses runs on. In particular, I assume terminals with colors and UTF-8 support.

Will it run any Lua lcurses program?

Some functions in lcurses have additional smarts. Teliva is consistent with the underlying ncurses.

What's with the name?

Teliva is the Tamil root for ‘clear’. Very much aspirational.

Coda

In addition to Lua 1.5, Teliva forks or depends on:

• The ncurses library for building text-mode user interfaces. (Alternative documentation)
• The lcurses binding for ncurses. (Documentation)
• The Kilo text editor. (Read more about it in this fantastic walk-through.)
• The luasocket library of networking primitives.
• The json.lua library for serializing/deserializing to JSON.

Send all praise to them, brickbats to me.