Emacs is malleable enough that someone implemented a whole screen reader in it.
The basic idea is that you have a library that lets you stick your own code at the beginning/end/around existing functions. So, someone did that for functions responsible for moving to the next/previous line/word/character, and they had a basic screen reader in place. In about 30 minutes.
Now, it's far more advanced, and, because of the malleability, you can "hack" information out of someone else's code if they don't provide it to you directly, which comes in very handy for such things.
As an aside, NVDA, the main screen reader for Windows at this point, is very malleable too. It's written in Python, so extensions can modify anything they wish. Amazing things have been built for it, including a whole remote access package, team-viewer style.
The basic idea is that you have a library that lets you stick your own code at the beginning/end/around existing functions. So, someone did that for functions responsible for moving to the next/previous line/word/character, and they had a basic screen reader in place. In about 30 minutes.
Now, it's far more advanced, and, because of the malleability, you can "hack" information out of someone else's code if they don't provide it to you directly, which comes in very handy for such things.
As an aside, NVDA, the main screen reader for Windows at this point, is very malleable too. It's written in Python, so extensions can modify anything they wish. Amazing things have been built for it, including a whole remote access package, team-viewer style.