This is **very** interesting question! 
When we recruit people to our company (we are working in Haskell everyday), we are basing on some classification between basic, intermediate and advanced stuff. These sections are shown below. I would love to hear what others are thinking about it and what from the below stuff would be widely considered as "basic Haskell knowledge", which would allow for full-time basic Haskell work.

Basics

  1. type classes
  2. instances
  3. functors, applicatives, monads, etc (http://www.haskell.org/haskellwiki/Typeclassopedia)
  4. functional dependencies
    1. Patterson condition
    2. Coverage condition
    3. Liberal coverage condition
  5. monad transformers

Intermidiate

  1. lens
  2. arrows
  3. free monads
  4. GADTs
  5. Type families
    1. closed type families
  6. existential datatypes
  7. RankNTypes
  8. church encoding

Advanced

  1. templateHaskell
  2. generics
  3. continuations
  4. delimited continuations


2014-07-25 0:44 GMT+02:00 Johan Larson <johan.g.larson@gmail.com>:
What does a programmer need to know to be proficient in "basic Haskell"?

For my money, basic programming skills are those that are required to
write programs for simple tasks in the common idioms of the language.
This means the practitioner should be able to read input from the
terminal or files, select/combine/reformat data, and output a result.
At this point, efficiency isn't really the point; only getting to a
correct answer without writing anything really weird matters.

In LYAH, I'd put the boundary at the end of chapter 9, which covers
the IO monad. At that point the reader has studied functions, lists,
tuples, types, recursion, higher order functions, four major modules,
and algebraic data types. Actually, some of the later topics in
chapter 8 (functors, kinds, recursive data structures) seem more like
intermediate material.

Thoughts?

--
Johan Larson -- Toronto, Canada
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