Talk:Haskell/Prologue: IO, an applicative functor

Initial remarks
This chapter is the result of a tricky compromise between the need of introducing  before   in a post-AMP/GHC 7.10 world and the desire of not ripping apart the organisation of the book (I wrote more about the rationale behind its original version in my userspace). While the resulting text brings in  from a very lean background, to avoid extending the discussion too much or presenting too many new topics at once, it does mobilise several threads that will be pursued further in the fourth unit, the most obvious of these being the issues around. Feedback on the text is most welcome! --Duplode (discuss • contribs) 22:03, 9 October 2016 (UTC)

Describing applicative operators in English
I'm curious: Is there an English language way to say the operators  and  ? If "less than star greater than" and "less than dollar greater than" is the most descriptive way we have, so be it, but I'd like to pronounce them correctly whenever I read code in my head. Mttpgn (discuss • contribs) 04:05, 3 June 2019 (UTC)


 * Perhaps surprisingly, there is no canonical pronunciation for them. One option is using "map" and "ap", respectively, after their near-synonyms with pronounceable names. For something with more of an infix feel and closer to plain English, I like "over" and "across", but that is just me. --Duplode (discuss • contribs) 02:03, 4 June 2019 (UTC)

Parsing operators
I have long thought that this chapter presents unnecessary difficulties for a beginner in that the reader needs a very good understanding of how binary operators are parsed. The book barely covers any of that, although up to this point it isn't a serious issue. But suddenly in this chapter unfamiliar operators are presented with no indication of fixity and are then used in various combinations which are only disambiguated by the fixity rules. Just including a few :i (op) displays when operators are introduced would help substantially. I have in mind people reading offline, perhaps on an ebook reader. The same comment applies to the next chapter introducing monads.

Rusticfig (discuss • contribs) 19:27, 8 November 2020 (UTC)


 * That's a really good observation. In addition to what you suggest, I think it would make sense to have a short chapter discussing the syntax of operators, perhaps next to the one about indentation in the sequencing of the book. Duplode (discuss • contribs) 14:55, 13 February 2021 (UTC)