Improvements and Next Steps for the Processing Language Server (LSP)

We’re revisiting the Processing Language Server with the goal of improving support for writing and editing Processing code outside the PDE.

Background

Several contributors have laid important groundwork for this effort:

• Initial work by @kgtkr was incorporated for Processing 4.1. They also built a minimal Processing LSP client for VSCode.
• Further work by @efratror was included in Processing 4.3 (see https://github.com/processing/processing4/issues/678 and https://github.com/processing/processing4/issues/690)
• As part of the pr05 grant in 2024, @diyaayay worked on another VS Code extension though it did not make use of the built-in LSP.

Proposed Improvements

We’d like to improve and extend the current functionality of the built-in LSP. Priorities are:

• Display parameter names in function signatures (e.g., copy(sx, sy, sw, sh, dx, dy, dw, dh)) should show named parameters
• "Go to declaration" for built-in functions and classes (linking to Processing source code when possible)
• Hover documentation for built-in functions and core classes
• Support for overloaded functions (e.g., colorMode(mode), colorMode(mode, max), colorMode(mode, max1, max2, max3))

If you're interested in contributing or discussing further, feel free to comment here.

Thanks again to everyone who has contributed to this work so far!

Start by reviewing the current built-in Processing Language Server and the prior work linked in this issue, including issues 564, 678, and 690. Compare its behavior with the listed priorities, then define a focused contribution whose completion can be checked against one specific LSP capability.