Denicek

Denicek is a computational substrate for document-oriented end user programming. It simplifies the implementation of programming experiences including collaborative source code editing, programming by demonstration, incremental recomputation, schema change control, end-user debugging and concrete programming.

Denicek represents a program as a series of edits that construct and transform a document consisting of data and formulas. Denicek provides three operations on edit histories: edit application, merging of histories and conflict resolution. The above programming experiences can be easily implemented by composing these three operations.

Running

Denicek is written in F# using Fable to target JavaScript. To run it, you will need .NET (version 8.0) and Node.js installed (version 22 works, others may too).

The process should be as simple as:

npm install
npm run start

This should do the trick. npm install will also run dotnet tool restore to install Fable. You can also run npm run build to build everything and npm run test to run tests (this runs tests directly on .NET, not via JavaScript).

You can then open running demo at http://localhost:8080.

How to use

This is an experimental prototype, so using it is tricky! The core of the system is a structure editor that you can use for creating documents. If you have a document you can navigate around using arrows:

• Left/Right - jump into the next element, going into all children
• Up/Down - jump over the next element, skipping all children

The editing of document is done using commands. If you know the command, just start typing it. Otherwise, you can type ? for search. For example, if you want to create an element, type ?add and you will see commands including "add record field". If you hit Enter, the start of the command will be selected and you can type the parameters. To construct hello world:

:title=<h1>      // Add <h1> element
[right arrow]    // Move inside it
:value=Hello!    // Add text to element
[left arrow]     // Move outside h1
<marquee title>  // Wrap it in marquee!

Use Alt+U to switch between the document view and source view. You can When you hit Alt, you will also get a pop-up with various other available commands.

Use Ctrl+Up / Ctrl+Down to navigate through the history. You can toggle the history panel (showing the past edits on the right) using Alt+H.

Running demos

The panel above lists various demos such as conf (add, rename, table, budget). Clicking on these will load the demo. This can also be used to illustrate the merging functionality. Here is how things work:

• Clicking conf will just replace what you have with a baseline history (shared with all version of the demo).
• Clicking any of add, rename, table, budget will merge whatever you have with extra edits that add some more functionality (support for adding speakers, rename one of the speakers, refactor as table, add budget calculation).

This means that you can see how merging works. For example:

• Click on conf, then add and table - This first adds a speaker and then reconciles table edits with those done by add and refactor all items into a table.
• Click on conf, then table and add - This first refactors the list into a table and then reconciles add edits with those done by table and insert speaker as a new table row.

In this case, there are no conflicts and we can merge edits both ways!