miniblog.

Over a sufficiently long time horizon, all code you write is legacy code.

ASTs typically discard comments, and that's usually what you want. The only time (AFAICS) that preserving comments is useful is for writing a code formatter. Could you write a formatter in terms of a list of lexemes? A CST is a non-trivial bit of code for one use case.

Difftastic has been cited in a paper! Modernizing SMT-Based Type Error Localization https://arxiv.org/abs/2408.09034 The authors use difftastic to work out which parts of a buggy program have actually changed, a great use case :)