[Haskell-cafe] what is basic Haskell?

Andrew Gibiansky andrew.gibiansky at gmail.com
Thu Jul 24 23:22:30 UTC 2014

Oh, that makes sense. If you regularly do stuff with OverlappingInstances,
that can definitely bite you :) I did not think about that since I tend to
avoid OverlappingInstances in my own work whenever possible. Makes sense,

I think it might make sense to have a list like this on a wiki somewhere,
honestly. Of course a lot of bikeshedding could go into the exact division
of topics, but it'd still be useful for something like this to exist

On Thu, Jul 24, 2014 at 4:19 PM, Wojciech Danilo <wojciech.danilo at gmail.com>

> Alex - we are making a very havy use of them (we are creating our own
> language, compiler and domain specific libraries) - but you are right - in
> other scenarios, they would be intermidiate (not advanced in my opinion).
> Andrew - I would disagree with point 1. If you are using
> OverlappingInstances and you are defining self-recursive instances,
> compiler will complain giving you no hints unless you know what you are
> doing (again, we are making ahvy use out of it, so I'm a little biased)
> Ad. 2) - you are right - they are in the intermediate section, because
> they are not hard to follow and understand. Additional, they are used a lot
> in reactive programming - but here I agree, they could go elsewhere.
> And of course you are right - there is a bunch of very busic stuff not
> covered by the list - maybe I should just add it there, to make this list
> more pure! :D
> 2014-07-25 1:14 GMT+02:00 Andrew Gibiansky <andrew.gibiansky at gmail.com>:
> The list there you have roughly corresponds to my intuitions, except for a
>> few minor things:
>> 1. Functional dependencies. --- I personally have used functional
>> dependencies and wrestled with things like the coverage condition, and
>> while I know I could easily look it up and would have no trouble
>> understanding it, I doubt I could tell you what each of those is without
>> looking it up. But I've never felt that knowing that is really worthwhile -
>> they're just things the compiler will complain about if I run into them
>> accidentally, and most programmers who have written enough of their own
>> instances probably get them right anyways. So I'm not really sure that
>> understanding those is necessary for being productive on a day-to-day
>> basis, and they seem a bit out of place on that list. Do you have a
>> particular reason they're there?
>> 2. Arrows -- I've been programming Haskell for a few years now, and only
>> run in to arrows *in practice* a few times. I've definitely seen a few
>> libraries migrating away from arrows towards applicative or monadic
>> interfaces instead. Do you use them often? I definitely feel like they're a
>> bit more on the esoteric side, while GADTs, free monads, lenses, type
>> families, and existential data types are things I encounter fairly
>> frequently. On the other hand, they seem to be a good model for FRP and
>> such, so maybe not. (Same goes for church encodings, but that's just a nice
>> bit of CS that people should know a bit :) )
>> On the whole, looks like a pretty good list that I agree with. Of course,
>> the "basic" list really includes a bunch more - knowledge of data types,
>> syntax, functions, laziness, etc.
>> -- Andrew
>> On Thu, Jul 24, 2014 at 4:01 PM, Wojciech Danilo <
>> wojciech.danilo at gmail.com> wrote:
>>> 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 at 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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