What I am trying to do (and what I found nothing about with careful googling) is to write a plugin that replaces certain characters (or character strings) with other characters, but only visually for the user. In the underlying file, the characters should stay unchanged. For instance, if I type a '\' in Haskell outside a string, I want it to be displayed as a 'λ', but in the file it should stay a '\', since that's what Haskell requires. The Haskell IDE Leksah has a feature like that, and I was wondering if it was possible to emulate that with a Sublime plugin.
I have no experience with plugin development as of yet, I wanted to ascertain first whether it is even possible to do what I am intending to.
Thanks in advance for any answers that might come this way.