prop-menu.el is an library for computing contextual menus from text properties and overlay properties. In particular, it's developed for idris-mode, where the compiler sends quite a lot of semantic annotations about the source code back to Emacs. This will allow relevant commands, such as documentation lookup, case-splitting pattern variables, and showing error details, to be built for each location in the buffer, with a single keybinding or mouse click giving easy access to the commands. Since I think this may be useful outside of idris-mode, I'm submitting it as a separate library. The package repository is at https://www.github.com/david-christiansen/prop-menu-el.