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Comment by bqmjjx0kac | Hacker News Reader

I got lost on the last example: `(foo (bar))` -> `(foo (novel) (bar))`. The diff that adds `novel` and a pair of parentheses seemed impossible -- wouldn't you also have to delete and re-add `bar`?

Writing this comment it occurs to me that the structural diff doesn't translate to plaintext very well, and thus is not accessible to folks with red-green colorblindness.

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Thanks for the feedback! I'll look to clarify the wording here. The failed example was a real output that difftastic gave in early versions.

I agree that the classic red/green colour scheme of diffs isn't great for colourblind users. I've asked a few colourblind developers and they were happy with terminal ANSI colours (which is what difftastic uses), because they can configure each colour individually.

I think that example is an error. What they possibly meant was you can perform the change by inserting “novel) (”, which may structurally translate to inserting “novel” in the bar list and then splitting that list.

Advanced diff tools usually allow configuring the colors, so that if the red/green is a problem, you can change it to red/blue or blue/yellow or whatever.

I don’t think it was an error, given how the article describes its handling of delimiters. In the example:

  (foo (bar))
  (foo (novel) (bar))

The balanced parentheses around bar “haven’t changed”, but the symbol between them “has”, and the balanced parentheses around bar were “added”. It’s a perfectly valid diff given the approach, even if it’s not ideal, as the author found.

The only way you could arrive at “novel) (” given the algorithm, I think, would be something like

  (foo (bar))
  (foo novel) ((bar))

(This might be off too, hard to write code on mobile)

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