That's weird, but I believe I remember seeing some DHH writings talking about coding in anger around the time he was defending cursing and sexually suggestive mostly-nude slides at Ruby confs[1]. I blew the phrase off as as a DHH-ism, thinking maybe he believed in trying to remain angry while coding or something crazy like that. Thanks for explaining the term!
I don't know what DHH meant, but the idiom "in anger" is used to mean "in seriousness", "for real" or "properly". Whether or not DHH meant the idiom, I do not know. But its likely.
For example: "I've been tinkering with emacs, but I've yet to use it in anger."
