underscore.io books

The people at underscore.io have made their books on Scala and functional programming free (or “donationware,” if you prefer). I’ve found the Advanced Scala with Cats book to be particularly good, and well worth a donation.

(Full disclosure: I didn’t pay for the Advanced Scala book when I first downloaded it, then went back and tried to pay for it, but the Gumroad website wouldn’t let me do that.)

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