Confusion regarding a passage in the "Kinds and some type-foo" section of learnyouahaskell.com

Question

I'm a Haskell noob who's working his way through the wonderful "Learn You A Haskell For Great Good". This question is related to a passage in the section called "Kinds and some type-foo" in chapter 8. The passage that reads:

"Making Frank an instance of Tofu is pretty simple. We see that tofu takes a j a (so an example type of that form would be Maybe Int) and returns a t a j. So if we replace Frank with j, the result type would be Frank Int Maybe."

This has me somewhat befuddled. In my mind the last sentence should read:

"So if we replace t with Frank, the result type would be Frank Int Maybe."

Any explanation as to where I'm going wrong would be much appreciated.

I'm with @ehird, it is an error of the book. You should warn the author about it. His email address is on the homepage of the book. — Riccardo T., Mar 27 '12 at 16:07
The error is still there, btw. I don't understand what the effort is in correcting such an obvious error... — Enlico, May 11 '20 at 19:08

score 12 · Accepted Answer · answered Mar 27 '12 at 15:43

12

You're not going wrong at all. It's an error in the book. Your proposed sentence is correct.

answered Mar 27 '12 at 15:43

ehird

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Confusion regarding a passage in the "Kinds and some type-foo" section of learnyouahaskell.com

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