Comment Feed for Channel 9 - C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 http://ecn.channel9.msdn.com/o9/previewImages/100/504213_100x75.jpg Channel 9 - C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 In Chapter 10, Declaring Types and Classes, Dr. Meijer teaches us about type declarations, data declarations, arithmetic expressions, etc.  In Haskell, a new name for an existing type can be defined using atype declaration:type String = [Char]String is a synonym for the type [Char].Like function definitions, type declarations can also have parameters. Type declarations can be nested, butnot recursive.Nested:type Pos   = (Int,Int) type Trans = Pos -> PosIllegal recursion:type Tree = (Int,[Tree])A completely new type can be defined by specifying its values using a data declaration:data Bool = False | TrueBool is a new type, with two new values False and True.Get the presentation slides hereChapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 en Fri, 24 May 2013 22:17:50 GMT Fri, 24 May 2013 22:17:50 GMT Rev9 Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 I'm so loving these lectures!

Thank you very much Charles and Erik for your work...you're doing a wonderful job!

I'm really looking forward to see the last three (or maybe four Smiley) lectures

posted by MarioTP

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954619360000000 Thu, 03 Dec 2009 18:32:16 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954619360000000 MarioTP Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Excellent job Erik and C !! We would love very much for you guys to cover some advanced topics in Haskell and Fuctional Programming (as i mentioned in chapter 9 thread ) Thanks and continue with the excellent work.

posted by fbrubacher

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954627840000000 Thu, 03 Dec 2009 18:46:24 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954627840000000 fbrubacher Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Me too! Smiley

 

Thank you.

 

Erik deserves most of the credit here, of course - he's doing the lectures. Me, I just had the idea to do lectures on Channel 9. FP was the clear choice to launch this new content type on C9 because we have spent so much time talking about functional programming over the years that we felt it appropriate to just focus on FP in the most efficient way possible - experts lecturing, teaching.

 

Keep on watching,

 

C

posted by Charles

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954629340000000 Thu, 03 Dec 2009 18:48:54 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954629340000000 Charles Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Still watching this episode, I just had to say I love how you tied "Theorems for free!" together with dependent typing as well as ADTs!

In progress...

posted by exoteric

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954630270000000 Thu, 03 Dec 2009 18:50:27 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954630270000000 exoteric Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 These lectures have been the highlight of my Thursdays. Smiley .  Thanks for taking the time to produce them. I’m looking forward to see this lecture tonight.

posted by paks8150

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954661610000000 Thu, 03 Dec 2009 19:42:41 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633954661610000000 paks8150 Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Today there is big snow in Calgary. I am enjoying the lecture on my Mac. Here is my type: snow a = Nothing | Big snow. Thank you Eric!

posted by chudq

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633955666890000000 Fri, 04 Dec 2009 23:38:09 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633955666890000000 chudq Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Erik: You are talking about "the expression problem" as still being a research subject. However, multimethods (as defined in the language Clojure) elegantly solves the problem?

 

posted by mbrodersen

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633960393430000000 Thu, 10 Dec 2009 10:55:43 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c633960393430000000 mbrodersen Re: C9 Lectures: Dr. Erik Meijer - Functional Programming Fundamentals Chapter 10 of 13 Eric, a very late question

 

In object oriented languages, we have the flexibility of defining sub-classes late after super class has been defined. The two definitions need not be done simultaneously. Moreover, there is no limit on the number of sub-classes baring the case of sealed types (which could still be circumvented using containment and defining casts).

In relation to the analogy of algebraic types and class hierarchies, what is the way in Haskell to extend the types as we can do in object oriented languages.

For example:

data Answer = No | Yes

data AnswerEx = FromAnswer Answer | Unknown

 

fromAnswerEx :: AnswerEx -> Answer

fromAnswerEx FromAnswer a = a

fromAnswerEx Unknown = No -- in Haskell we have to generate a value of Answer type here

 

We could surely define functions for explicit conversion e.g. fromAnswerEx but the compiles can not use them automatically. In code given below we have to use the explicit conversions.

 

answers = [Yes, No, fromAnswerEx Unknown, fromAnswerEx FromAnswer Yes]

 

The following will not work.

 

answers = [Yes, No, Unknown, FromAnswer Yes]

 

It is possible there in object oriented languages.

 

Is there any pattern/idiom in Haskell to achieve same?

 

posted by A N Satrawala

]]> http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c634007266260000000 Tue, 02 Feb 2010 16:57:06 GMT http://channel9.msdn.com/Series/C9-Lectures-Erik-Meijer-Functional-Programming-Fundamentals/C9-Lectures-Dr-Erik-Meijer-Functional-Programming-Fundamentals-Chapter-10-of-13#c634007266260000000 A N Satrawala