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Mark Elston (133) [Avatar] Offline
I ran into a use of the $ operator in one of the listings and was a bit confused by it. I went back and scoured the entire document (I think) and couldn't find where this was explained. I see that later you explain the fmap / <$> operation, but I don't see the $ operator explained anywhere even though you use it. I had to look it up on StackOverflow to figure out what it does.
Will Kurt (21) [Avatar] Offline
The $ does make an appearance in the last unit (not yet in the MEAP) which I'll be the first to admit is a very odd place for it. I think I'll go back and add a note in unit 1 so it's not so confusing (or maybe in the revised lesson 0). As you have no doubt noticed, the $ operator is used very heavily in real world Haskell. The one reason it's missing is I never ended up finding a place where it felt natural to introduce it. The other is that for beginners I find that parentheses are often much more readable.

Regardless this is definitely a glaring omission from the current book and it will be remedied before publication. Thanks again for your feedback!
Mark Elston (133) [Avatar] Offline
Thanks. I was sure I saw it somewhere in the current MEAP. Maybe not.