Talk:History of Haskell/Version 1

Comments on "The History of Haskell" (draft)

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Simonpj 18:51, 14 July 2006 (UTC) Simon PJ. Here is an example comment

BerniePope I hope you don't mind, but I've taken the liberty of breaking this up into sections, so that it is easier to find out what has been said already. This seems to be especially useful for typos etc. Please feel free to add other sections if you think they are necessary. I've also made the page numbers bold, and put them into page order (where possible).

Title suggestions

JaredUpdike 20:38, 14 July 2006 (UTC) Other ideas for a title: The History of Haskell: Unsuccessfully Avoiding Success or something using the motto "Avoid success at all costs." Or perhaps Success Considered Harmful, or, A History of Haskell or Doomed to Succeed quoting Hoare (although this sounds somewhat self-congratulatory).

GaneshSittampalam 09:19, 15 July 2006 (UTC) I really like the "eager to be lazy" title.

Typos, spelling, grammar, formatting and expression

BerniePope 15:42, 15 July 2006 (UTC) Typo: page 2, column 2, "Rod Bustall" should be "Rod Burstall".

BerniePope 15:42, 15 July 2006 (UTC) Spelling: page 3, column 1, "confernce".

On page 4 after the list of goals, it seems that the following sentence ("We agreed to base it on an existing language, namely OL.") should be preceeded by a line break (it now starts on the same line as the sixth goal).

JaredUpdike 22:00, 14 July 2006 (UTC) page 9 Section 3.8, last paragraph, syntax error: should be "Miranda is still in use today: it is still taught in some institutions", missing word. (Sec 4.2 This tradition was honed by Moses Schonfinkel and Haskell Curry, and came to be called currying. I half expected a joke following this, saying [it was] called currying, luckily, and not schonfinkeling.) Same section, typo: is a list of lists should be in a list of lists.

BerniePope 15:42, 15 July 2006 (UTC) Expression. page 9. It says "Haskell did not adopt Miranda's abstract data types, using its module system instead." It is not clear whose module system it is using. Perhaps it should read "using a module system instead." ?

BerniePope 15:56, 15 July 2006 (UTC) Tense. page 12. Section 5.1, algebraic data types. It says "In general, every algebraic data type specified...", should that be "specifies" ? or perhaps even better "In general, algebraic data types specify" ?

Ruiz 12:04, 16 July 2006 (UTC) Comment. page 12. If I am not mistaken, the Fermat's Last Theorem example only generates (1,1,z) triplets.

BerniePope 16:15, 15 July 2006 (UTC) Tense. page 13. Section 5.3 Abstract types. It says "This had the advantage ...". Perhaps it should be: "This has the advantage", since Miranda still exists, and the advantage still holds. Later in the same paragraph the expression about adopting the feature in Haskell is a bit awkward. Perhaps it could read: "It is not clear how to adapt Miranda's method of defining abstract data types to type classes, and that is one reason we chose a different solution." ?

BerniePope 16:27, 15 July 2006 (UTC) Typo. Section 5.6, page 14 and in Bibliography. Godel's name in citation missing the 'o'.

BerniePope 05:41, 16 July 2006 (UTC) Comment. page 15, column 1. "practical comprehensibility" is a bit of a mouthful. Perhaps "pragmatism" would suffice?

BerniePope 06:11, 16 July 2006 (UTC) Typo (possibly). page 16. Section 6.4, multi-parameter type classes. "They gave the following example: second.". Should the "second" be there?

BerniePope 06:56, 16 July 2006 (UTC) Typo, page 16. The code "n = (x + y)", perhaps drop the redundant parens?

BerniePope 07:19, 16 July 2006 (UTC) page 17. Choice of identifier. In the code "f (MkT x f) = f x". Perhaps the inner or outer "f" should be renamed? Also, is there a more compelling example than this one?

BerniePope 07:16, 16 July 2006 (UTC) Typo. page 17. "patter-matching" -> "pattern-matching".

BerniePope 07:26, 16 July 2006 (UTC) Expression. page 17. Perhaps drop "rather than explicitly". This is implied by the previous "happens implicitly".

BerniePope 07:38, 16 July 2006 (UTC) Typo. page 18. In lexically scoped type variables, it says the type of xcons is "forall a. a -> a". Do you mean: "forall a . [a] -> [a]"?

BerniePope 08:39, 16 July 2006 (UTC) Typesetting. page 22. Sometimes the "IO monad" is written where "IO" is in typewriter font, and other times it is in times roman, and other times it is written "I/O". This may be an intentional distinction, but maybe the notation can be unified?

JaredUpdike 04:27, 15 July 2006 (UTC) page 25. Section 9.2 misspelling "existance" should be "existence" third to last paragraph. Sec. 9.5 , page 27, second to last paragraph. test bad should be test bed.

BerniePope 12:33, 16 July 2006 (UTC) Typo. page 28. Section 10.2, paragraph 2. "who had by thus time" -> "who had by this time".

Weihu 21:35, 15 July 2006 (UTC) Typo: page 31, column 2, "a central them" should be "a central theme".

GaneshSittampalam 09:18, 15 July 2006 (UTC) Section 11.2.3 page 34 typo "unsagePerformIO".

Typo on page 39: Another example is that Linspire’s toold must handle legacy data formats. --Neil Mitchell 15:23, 14 July 2006 (UTC)

General comments

BerniePope 15:42, 15 July 2006 (UTC) Comment. page 7. Section 3.3, third paragraph. Rather than talk about "div" (are the first quote marks backwards?), perhaps you could say - "for example, Miranda's type system allows floating point values to be given to functions which are only defined on the integer subset of num, thus turning a static error into a dynamic one."

BerniePope 15:42, 15 July 2006 (UTC) Comment. page 10. Section 4.1, layout. It says "The rules are simple ...". I think this is a contentious issue. Recent discussions on the Haskell Prime mailing list [1] suggested a contrary view. How many Haskellers actually know the rules? Perhaps it would be more accurate to say that experience shows it is not hard to adopt a style of programming which stays within the rules.

BerniePope 15:42, 15 July 2006 (UTC) Comment. Footnote 2 on page 10 says the Scheme authors took a more Draconian approach with respect to operators, though it doesn't actually say what that means. On the off chance that someone reading the paper doesn't know Scheme, it might be worth elaborating on that point.

BerniePope 15:42, 15 July 2006 (UTC) Comment. page 12. Section 4.4. Near the end of the section you give an example of "where" being attached to a declaration. I think the example function "f" is rather obscure, perhaps there is a better example? Maybe one from the Prelude? Also, there seems to be another point you could make here. Due to laziness we get some more freedom in the way that we write where clauses. For instance, the thing being defined in the where clause may only be well defined in a subset of the alternatives. But that doesn't matter because we will only evaluate the thing if and when it is needed, not before.

BerniePope 15:42, 15 July 2006 (UTC) Comment. page 12. Section 4.5, list comprehensions. Perhaps it is worth noting the Haskell does not have the diagonalisation operator like Miranda. It may also be worth remarking on why this is so. Surely it was considered.

BerniePope 16:05, 15 July 2006 (UTC) Comment. page 13. Section 5.3 Abstract types. It says that the type has one constructor. Is it really necessary to limit the type to just one constructor? Surely it is enough that the constructors of the type are not exported, regardless of how many there are?

BerniePope 05:28, 16 July 2006 (UTC) Comment. page 14. Section 6.1, Type classes. Perhaps it should mention that eqInt is primitive equality on integers, maybe as a comment in the code.

BerniePope 05:54, 16 July 2006 (UTC) Comment. page 15. Section 6.2 Monomorphism restriction. This marks one of the most unusual aspects of the language, especially in the Language Report. In particular, it is motivated by operational semantics --- sharing --- but the rest of the Report is largely silent on the issue. I think the Report says something to the effect of "programmers expect sharing to be preserved", but there is not much else in the Report to back this statement up. Perhaps you could tie this back to the discussion in Section 3.4 (Haskell has no formal semantics). Also, I think it would be reasonable to say "GHC provides a flag to suppress the restriction", without actually naming the flag.

BerniePope 06:02, 16 July 2006 (UTC) Comment. page 15. Section 6.2 Higher kinded polymorphism. It says "Here, the type variable m has kind *->*". It seems like the reader is already supposed to know what a kind is at this point. Perhaps the section could provide a little introduction to the concept of kinds first. Another thing about kinds is that they are sort of shadowy figures that seem to lurk in the background of Haskell. For instance they have no syntactic counterpart in Haskell 98. It can be quite daunting for beginners when they get a kind error.

BerniePope 07:30, 16 July 2006 (UTC) Comment. page 17. Section 6.6 Implicit parameters. Perhaps contrast this approach to a Reader monad?

BerniePope 07:44, 16 July 2006 (UTC) Comment. page 18. Arrows. It doesn't really say what arrows are, except that they are like monads, but more general. Perhaps this could be elaborated, maybe with some mention of the intuition that arrows generalise things which are somehow composable? Perhaps an example of an arrow which cannot be done with a monad?

BerniePope 08:14, 16 July 2006 (UTC) Comment. page 20. Section 7.2 Monads. It says that "Checking that the laws hold provides a reassuring sanity check when defining a new monad." Perhaps you could elaborate on exactly what we are checking, and subsequently reassured about. It says earlier that the laws show associativity and identity, but is there are more "programmer oriented" view of what this means?

BerniePope 08:22, 16 July 2006 (UTC) Comment. page 20. Section 7.2 Monads. It says monads were helpful in structuring programs, including "the Haskell compiler itself". This sounds like there was a single Haskell compiler. Perhaps it should be "exisiting Haskell compilers"?

BerniePope 08:22, 16 July 2006 (UTC) Comment. page 20. Section 7.2 Monads. One of the ongoing issues with monads is combining them together. Perhaps you could mention some of the attempts at doing this, such as monad transformers.

Hoan 12:45, 15 July 2006 (UTC) On page 33 it says that Ruby on Rails is a continuation based framework. I think thats wrong. PS. Its a riveting read.

BerniePope 07:57, 16 July 2006 (UTC) Overall. Names of people. I've noticed that sometimes people are referred to by their whole name, whilst others are referred to by just their family name. Perhaps there is an underlying method here, but it wasn't clear to me. Perhaps it is that the first reference gets a full name, and subsequent ones are just the family name? Is that always the case?