X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=translating_between_OCaml_Scheme_and_Haskell.mdwn;h=b893896283a27cc5f027b3a1bd72561957835727;hp=4a4287a1e776a13524b7db78d2ef9de43fb83b00;hb=8e24378981bd4095fe580475cf6a530e168965b1;hpb=a7d3954c76604eea8d2c392c5eb2f9d11891460a diff --git a/translating_between_OCaml_Scheme_and_Haskell.mdwn b/translating_between_OCaml_Scheme_and_Haskell.mdwn index 4a4287a1..b8938962 100644 --- a/translating_between_OCaml_Scheme_and_Haskell.mdwn +++ b/translating_between_OCaml_Scheme_and_Haskell.mdwn @@ -140,9 +140,9 @@ There are some more hints about Scheme [here](/assignment8/) and [here](/week1/) We will however try to give some general advice about how to translate between OCaml and Haskell. * Again, it may sometimes be useful to [try Haskell in your web browser](http://tryhaskell.org/) -* There are many Haskell tutorials and textbooks available. This is probably the most actively developed: [Haskell Wikibook](http://en.wikibooks.org/wiki/Haskell) -* [Yet Another Haskell Tutorial](http://www.cs.utah.edu/~hal/docs/daume02yaht.pdf) (much of this excellent book has supposedly been integrated into the Haskell Wikibook) -* All About Monads has supposedly also been integrated into the Haskell Wikibook +* There are many Haskell tutorials and textbooks available. This is probably the most actively developed: [Haskell wikibook](http://en.wikibooks.org/wiki/Haskell) +* [Yet Another Haskell Tutorial](http://www.cs.utah.edu/~hal/docs/daume02yaht.pdf) (much of this excellent book has supposedly been integrated into the Haskell wikibook) +* All About Monads has supposedly also been integrated into the Haskell wikibook * (A not-so-)[Gentle Introduction to Haskell](http://web.archive.org/web/http://www.haskell.org/tutorial/) (archived) * [Learn You a Haskell for Great Good](http://learnyouahaskell.com/) @@ -183,15 +183,17 @@ We will however try to give some general advice about how to translate between O type Weight = Integer type Person = (Name, Address) -- supposing types Name and Address to be declared elsewhere - then you can use a value of type `Integer` wherever a `Weight` is expected, and vice versa. `newtype` and `data` on the other hand, create genuinely new types. `newtype` is basically just an efficient version of `data` that you can use in special circumstances. `newtype` must always take one type argument and have one value constructor. For example: + then you can use a value of type `Integer` wherever a `Weight` is expected, and vice versa. + + `newtype` and `data` on the other hand, create genuinely new types. `newtype` is basically just an efficient version of `data` that you can use in special circumstances. `newtype` must always take one type argument and have one value constructor. For example: newtype PersonalData a = PD a You could also say: - data PersonalData a = PD a + data PersonalData2 a = PD2 a - And `data` also allows multiple type arguments, and multiple variants and value constructors. + And `data` also allows multiple type arguments, and multiple variants and value constructors. OCaml just uses the one keyword `type` for all of these purposes: @@ -201,7 +203,7 @@ We will however try to give some general advice about how to translate between O * When a type only has a single variant, as with PersonalData, Haskell programmers will often use the same name for both the type and the value constructor, like this: - data PersonalData a = PersonalData a + data PersonalData3 a = PersonalData3 a The interpreter can always tell from the context when you're using the type name and when you're using the value constructor. @@ -670,6 +672,11 @@ Haskell has more built-in support for monads, but one can define the monads one which can be translated straightforwardly into OCaml. + For more details, see: + + * [Haskell wikibook on do-notation](http://en.wikibooks.org/wiki/Haskell/do_Notation) + * [Do-notation considered harmful](http://www.haskell.org/haskellwiki/Do_notation_considered_harmful) + * If you like the Haskell do-notation, there's [a library](http://www.cas.mcmaster.ca/~carette/pa_monad/) you can compile and install to let you use something similar in OCaml. * In order to do any printing, Haskell has to use a special `IO` monad. So programs will look like this: