websocket-editor

A simple web-based text editor which interacts bidirectionally with a Haskell backend server via websockets.

The intended use case is live-coding and simple IDE prototypes. Compared to a full-featured IDE like VSCode with LSP, this is very lightweight and allows live content feedback from the server.

The editor component is CodeMirror 5.60 by Marijn Haverbeke: https://codemirror.net/.

Multiple buffers

The server has the responsibility to maintain the content of the buffers. There is a simple tab-based interface to select buffers.

LaTeX-style unicode input

Using the d command below, we can implement a simple LaTeX-style unicode method: Simply type \alpha and press TAB to finalize (or autocomplete, if there is a unique completion).

Communication protocol

The communication protocol is a very simple, ad-hoc text-based encoding:

The client (the web-based editor) can send the following message:

u,l1:c1-l2:c2,replace    # the buffer was updated
b,<idx>                  # change the active buffer (indexing from zero)
l                        # list the existing buffers

The server can send the following messages:

f,text                   # replaces the "feedback pane"          
e,text                   # replaces the "error pane"      
c,text                   # replaces the editor content      
d,l1:c1-l2:c2,replace    # applies an atomic update on the editor buffer      
v,50                     # sets the vertical split ratio 
h,75                     # sets the horizontal split ratio 
l,["name1","name2"]      # returns a list of buffers

which has the following meanings:

• f replaces the content of the "feedback pane"
• e replaces the content of the "error pane"
• c replaces the content of the editor
• d applies an atomic update on the editor buffer
• v sets the vertical split ratio (percentage, the size of the left pane)
• h sets the horizontal split ratio (percentage, the size of the top pane)