Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-18 Thread Jay Sulzberger
When I was last on the best rooftop in the Mid Upper West Side of Manhattan I was told of the work on logical relations. I did not know of this three decades old line of work. I have grabbed http://homepages.inf.ed.ac.uk/gdp/publications/Par_Poly.pdf To me, the style is comfortable and the mat

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-16 Thread Jay Sulzberger
On Wed, 15 Aug 2012, wren ng thornton wrote: On 8/13/12 5:42 PM, Jay Sulzberger wrote: One difficulty which must impede many who study this stuff is that just getting off the ground seems to require a large number of definitions of objects of logically different kinds. (By "logic" I mean rea

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-15 Thread wren ng thornton
On 8/13/12 5:42 PM, Jay Sulzberger wrote: One difficulty which must impede many who study this stuff is that just getting off the ground seems to require a large number of definitions of objects of logically different kinds. (By "logic" I mean real logic, not any particular formalized system.) We

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-13 Thread Jay Sulzberger
On Thu, 9 Aug 2012, wren ng thornton wrote: On 8/8/12 9:41 PM, Jay Sulzberger wrote: Haskell's type classes look to me to be a provision for declaring a signature in the sense of the above article. Just to clarify this in the context of my previous post, type classes define signatures in

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-10 Thread Jay Sulzberger
On Thu, 9 Aug 2012, Patrick Browne wrote: On 09/08/12, Jay Sulzberger wrote: Here we are close to the distinction between a class of "objects which satisfy a condition" vs "objects with added structure", for which see: ? http://math.ucr.edu/home/baez/qg-spri

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-09 Thread wren ng thornton
On 8/8/12 9:41 PM, Jay Sulzberger wrote: Haskell's type classes look to me to be a provision for declaring a signature in the sense of the above article. Just to clarify this in the context of my previous post, type classes define signatures in two significantly different ways. (1) The first

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-09 Thread Tom Nielsen
Hello, On Thu, Aug 9, 2012 at 1:52 PM, Tillmann Rendel < ren...@informatik.uni-marburg.de> wrote: Note that many type classes in Haskell have equations annotated as > comments. For example, the monad laws are mentioned in the documentation of > the Monad type class: > One of the reasons why I ch

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-09 Thread Tillmann Rendel
Hi, Patrick Browne wrote: Haskell type classes seem to be signature only (no equations, ignoring default methods) so in general they provide an empty theory with no logical consequences. Note that many type classes in Haskell have equations annotated as comments. For example, the monad laws a

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-09 Thread Patrick Browne
On 09/08/12, Jay Sulzberger wrote:Here we are close to the distinction between a class of "objectswhich satisfy a condition" vs "objects with added structure", forwhich see:  http://math.ucr.edu/home/baez/qg-spring2004/discussion.html  http://ncatlab.org/nlab/show/stuff,+structure,+propertyoo--JS

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Jay Sulzberger
On Wed, 8 Aug 2012, Ertugrul S??ylemez wrote: Patrick Browne wrote: Gast [1] describes a 3 level hierarchy of Haskell objects using elementOf from set theory: value?? *elementOf*?? type?? *elementOf*?? class This hierarchy is pretty arbitrary and quickly runs into problems with some typ

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Richard O'Keefe
On 9/08/2012, at 11:11 AM, wren ng thornton wrote: > > Notably, a type class instantiated with all its arguments is not itself a > type! All the comparisons of Haskell typeclasses with Java classes answered in one brief lucid sentence. ___ Haskell-

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread wren ng thornton
On 8/8/12 3:36 PM, Patrick Browne wrote: On 08/08/12, *Ertugrul Söylemez * wrote: So you basically just mean class (Functor f) => Applicative f Yes, but I want to know if there is a simple mathematical relation between the classes and/or their types Let us introduce the notion of "

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Patrick Browne
On 08/08/12, Ertugrul Söylemez wrote:So you basically just mean    class (Functor f) => Applicative fYes, but I want to know if there is a simple mathematical relation between the classes and/or  their typesBut from your emails the original hierarchy seems to have been superseded, and my expectat

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Ertugrul Söylemez
Patrick Browne wrote: > > > If we include super-classes would the following be an appropriate > > > mathematical representation? > > > > What is a superclass?  What are the semantics? > > I assume that like a normal class a super-class *defines* a set > operations for types, but it is not *a set*

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Patrick Browne
On 08/08/12, Ertugrul Söylemez wrote:> If we include super-classes would the following be an appropriate> mathematical representation?What is a superclass?  What are the semantics?I assume that like a normal class a super-class *defines* a set operations for types, but it is not *a set* of types.

Re: [Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Ertugrul Söylemez
Patrick Browne wrote: > Gast [1] describes a 3 level hierarchy of Haskell objects using > elementOf from set theory: > > value  *elementOf*  type  *elementOf*  class This hierarchy is pretty arbitrary and quickly runs into problems with some type system extensions. You can find out whether the

[Haskell-cafe] 3 level hierarchy of Haskell objects

2012-08-08 Thread Patrick Browne
Gast [1] describes a 3 level hierarchy of Haskell objects using elementOf from set theory:value  *elementOf*  type  *elementOf*  classQuestionIf we include super-classes would the following be an appropriate mathematical representation?value *elementOf*  type  *elementOf* class  *subSet* super-clas