Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-26 Thread Pablo Nogueira
Another opinion in case you need more:

TAPL is excellent for self-study. There are solutions for most
interesting exercises. And every type system presented comes with a
downloadable implementation. You can practice with it and change it.
Do not hesitate to get it. I also recommend Cardelli's papers on types
which are free to obtain.

The Basic Category Theory book is, as the title says, "basic". It is a
sort of polished study notes (and I recall Pierce saying something
along this line in the introduction). Several examples and exercises
are taken from Goldblatt's "Topoi, the Categorical Analysis of Logic",
whose first chapters are a good starting point in Category theory but
he introduces category-theoretic concepts from set-theoretic ones and
it can be hard to abstract properly from one example.  Pierce's book
is well-written, introductory, there's nice stuff on cartesian closed
categories and F-algebras, and the best thing is its excellent
annotated bibliography which will help you to move on. Given its price
and size, I think its worth.

You'll need more stuff. There are books and tutorials out there.
MacLane I guess is a must, if only for breadth and precision. There's
Steve Awodey's book (Oxford University Press). I found Harold Simmon's
notes "Category Theory in four easy movements" enjoyable and readable,
especially the stuff on limits. Lawere's book mentioned by others is
also fun. Fokkinga has an excellent introduction to category theory
from a calculational standpoint, with notation and concepts used in
the Bananas paper. There is also Barr and Wells's third edition. And
of course, Mitchell's encyclopedic "Foundations for Programming
Languages".

To conclude, there are loads of sources and for self study, I'd
recommend to use several books and several tutorial notes, if only to
contrast approaches, definitions, to have exercises and solutions,
etc. And there's the wikipedia as well.
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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Derek Elkins
On Tue, 2007-09-25 at 16:18 -0500, Creighton Hogg wrote:
> 
> 
> On 9/25/07, Philippa Cowderoy <[EMAIL PROTECTED]> wrote:
> On Tue, 25 Sep 2007, Seth Gordon wrote:
> 
> > Are Benjamin C. Pierce's _Types and Programming Languages_
> and/or _Basic
> > Category Theory for Computer Scientists_ suitable for
> self-study?
> >
> 
> Basic Category Theory depends on your mindset somewhat. TaPL
> is great 
> though, and frequently recommended. The follow-up is also
> good.
> 
> Basic Category Theory is cute, but I think the exercises are sometimes
> phrased strangely.  In some ways, the book makes more sense if you've
> already seen these ideas once & are trying to get a more CS
> perspective of the math.  I'll probably be alone in this, but I think
> Mac Lane is a fantastic book for learning category theory.  It's hard,
> but if you trudge along and do the exercises you learn quite a bit.
> It's fun! 

I didn't learn Category Theory from Mac Lane (Categories for the Working
Mathematician for those out of the know), but I agree that it is a very
good introduction and an enjoyable read.  It does have good exercises.
It should also make a passing good reference.

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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Dan Weston
The absolute easiest, clearest, and most entertaining book on Category 
Theory (which I highly recommend) is:


Conceptual Mathematics: A First Introduction to Categories (Paperback)
by F. William Lawvere and Stephen Hoel Schanuel, $25

It literally reads like a series of college lectures (called Article), 
each followed by study sections (called Sessions), complete with fake 
dialog with fake students asking the questions that are probably on your 
mind while reading the Articles.


It has a tone so conversational that working mathematicians will run 
screaming, but I have found it highly enlightening. With hardly a proff 
in sight, this is definitely the starter book par excellence of Category 
Theory.


Here is a random excerpt on page 25, a dialog between Chad and the 
Professor:


PROFESSOR: Is this correct? Not quite, because we are supposed to draw 
two maps, and the thing draw for h . g is not a map; one of the points 
of the domain of h . g has been left without an assigned output. This 
deficiency won't matter for the next step, because that information is 
going to get lost anyhow, but it belongs in this step and it is 
incorrect to omit it. Chad's trouble was that in drawing h . g, he 
notices that the last arrow would be irrelevant to the composite (h . g) 
. f, so he left it out.


CHAD: It seems the principle is like in multiplication, where the order 
in which you do things doesn't matter; you get the same answer.


PROFESSOR: I am glad you mention order. Let me give you an example...

I defy you to be scared by this book. There are an obscene amount of 
diagrams illustrating the points as well, along with numerous (and 
redundant) exercises to make sure you are getting it all.


Dan Weston

Seth Gordon wrote:
Are Benjamin C. Pierce's _Types and Programming Languages_ and/or _Basic 
Category Theory for Computer Scientists_ suitable for self-study?


(Do they have problem sets that can be checked by either looking up 
answers in The Back of the Book, or by trying to compile/run some code 
that the student writes?)


FWIW, my formal math education--well, all the formal math education that 
I can remember at this point--stopped at freshman calculus plus one 
semester of statistics.

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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Creighton Hogg
On 9/25/07, Philippa Cowderoy <[EMAIL PROTECTED]> wrote:
>
> On Tue, 25 Sep 2007, Seth Gordon wrote:
>
> > Are Benjamin C. Pierce's _Types and Programming Languages_ and/or _Basic
> > Category Theory for Computer Scientists_ suitable for self-study?
> >
>
> Basic Category Theory depends on your mindset somewhat. TaPL is great
> though, and frequently recommended. The follow-up is also good.


Basic Category Theory is cute, but I think the exercises are sometimes
phrased strangely.  In some ways, the book makes more sense if you've
already seen these ideas once & are trying to get a more CS perspective of
the math.  I'll probably be alone in this, but I think Mac Lane is a
fantastic book for learning category theory.  It's hard, but if you trudge
along and do the exercises you learn quite a bit.  It's fun!
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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Stefan Holdermans

Seth,

You asked:

Are Benjamin C. Pierce's _Types and Programming Languages_ and/or  
_Basic

Category Theory for Computer Scientists_ suitable for self-study?


And Tim answered:


Graduate-level textbooks don't have answers in the back of the book,
as a rule. In TAPL, some of the questions involve writing code, but
others don't. If you're approaching this book, you ought to be at a
point where you can check your own sanity. Better yet, find a study
partner to discuss the problems with!


That said, TAPL does come with solutions for the better part of the  
exercise set.


Cheers,

  Stefan
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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Philippa Cowderoy
On Tue, 25 Sep 2007, Seth Gordon wrote:

> Are Benjamin C. Pierce's _Types and Programming Languages_ and/or _Basic
> Category Theory for Computer Scientists_ suitable for self-study?
> 

Basic Category Theory depends on your mindset somewhat. TaPL is great 
though, and frequently recommended. The follow-up is also good.

> (Do they have problem sets that can be checked by either looking up 
> answers in The Back of the Book, or by trying to compile/run some code 
> that the student writes?)
> 

TaPL does.

-- 
[EMAIL PROTECTED]

A problem that's all in your head is still a problem.
Brain damage is but one form of mind damage.
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Re: [Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Tim Chevalier
On 9/25/07, Seth Gordon <[EMAIL PROTECTED]> wrote:
> Are Benjamin C. Pierce's _Types and Programming Languages_ and/or _Basic
> Category Theory for Computer Scientists_ suitable for self-study?
>
> (Do they have problem sets that can be checked by either looking up
> answers in The Back of the Book, or by trying to compile/run some code
> that the student writes?)
>

Graduate-level textbooks don't have answers in the back of the book,
as a rule. In TAPL, some of the questions involve writing code, but
others don't. If you're approaching this book, you ought to be at a
point where you can check your own sanity. Better yet, find a study
partner to discuss the problems with!

I haven't gotten past the "watch it collect dust while sitting on my
coffee table" point with the category theory book, but I can tell you
that none of the problems in that one involve writing code.

Cheers,
Tim

-- 
Tim Chevalier * catamorphism.org * Often in error, never in doubt
"Ninety-nine percent of everything that is done in the world, good and
bad, is done to pay a mortgage. The world would be a much better place
if everyone rented." -- Christopher Buckley
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[Haskell-cafe] Pierce on type theory and category theory

2007-09-25 Thread Seth Gordon
Are Benjamin C. Pierce's _Types and Programming Languages_ and/or _Basic 
Category Theory for Computer Scientists_ suitable for self-study?


(Do they have problem sets that can be checked by either looking up 
answers in The Back of the Book, or by trying to compile/run some code 
that the student writes?)


FWIW, my formal math education--well, all the formal math education that 
I can remember at this point--stopped at freshman calculus plus one 
semester of statistics.

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