Using flymake in emacs to validate html as you type February 23, 2009 at 11:46 pm 3 comments Flymake is a general emacs plugin which allows you to run an external validator against a buffer’s content and visually report errors. The effects are quite similar to the red underlining you will see in some IDEs (e.g visual studio) – but can, with some work, be used for any file format with a validator.