Programming languages are not really just lines of text. Diffs from two different changes to a source file are not necessarily composable, even if there are no overlapping changes. Program code has syntax, and this syntax is knowable, even in the case of the most dynamic of languages (such as those with configurable readers such as Common Lisp). A source file, if it isn't broken, represents a particular structured object, an abstract syntax tree.

We should be able to leverage this.