It would be very useful to have an in-app purchase for language refs or api docs of many kinds. It could be an option in the files sidebar, so that one could access the language reference and leave it open in the sidebar while one codes so its very easy reference. You could offer it as an in-app purchase for each language and let people get the languages they want. I would definitely buy 5-6 of them almost immediately. Only points would be to make sure they are quite thorough, as in not incomplete. I've bought many other language ref apps and they are often woefully incomplete, not mildly, like the css pro language ref app doesn't have all of CSS3 in it, missing gradients, animation, etc., etc., The jquery one doesn't have the templating library, the PHP one doesn't have msqli. These are all very common, so its not like its real obscure things missing. But if it was done well, this could be a very good add to an already great app. I'd buy several.
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