Closures look like magic to those who don't know them. So you might try
something like this (which I have not compiled BTW):
-- Haskell version
data Train = Train {departs :: Time, platform :: Int }
departsBefore :: Time - Train - Bool
departsBefore t train = t departs train
Yep - I've seen it in course work I've set in the past - random walk
through the arrangement of symbols in the language (it was a process
algebra work and proof system to check deadlock freedom).
... but ...
Haskell even helps those people - if you've created something that
works (and you are
On 18/04/07, R Hayes [EMAIL PROTECTED] wrote:
One of the truly powerful things about Haskell is the short distance between
theory and practicality. The problem is how to demonstrate this
convincingly. The ability to prove a program's correctness is regularly
trotted out for show in this arena
Dougal Stanton wrote:
*QuickCheck is a really powerful way to work.*
The real pain in the butt with unit tests is having to write the damn
things. Especially for corner cases - if they were easy to reason
about they wouldn't really be corner cases, would they? QC allows you
to sidestep
Dougal Stanton wrote:
On 18/04/07, R Hayes [EMAIL PROTECTED] wrote:
One of the truly powerful things about Haskell is the short distance
between
theory and practicality. The problem is how to demonstrate this
convincingly. The ability to prove a program's correctness is regularly
trotted
I guess it is time to give my two cents on this topic I am definitely
not an expert Haskell programmer I am a mere hobbyist I make my bread
coding Java/C++/C.
I think the two things I like most about Haskell are
1. Its methods of combination Lazy Eval, Function composition and Higher
order
On 4/18/07, Taillefer, Troy (EXP) [EMAIL PROTECTED] wrote:
I have to strongly disagree with the statement that developers like to
debug. Debugging is necessary because you can't reason about any
sizeable piece of code just is not tractable even in Haskell. Now
automated tools for reasoning
Here here.
This reminds me of a recent discussion on the cafe. Thee OP amounted
to: What are the monad laws good for?. The answer was: It means the
monad doesn't do surprising things and its behavior is congruent with
the basic intuitions of sequenced computation.
In my eyes, proving nice
I still love Haskell, but...
since the language doesn't do batshit insane things behind your back
- Hmmm... I'd contend that the Haskell language is the one language that
does the most batshit insane things behind your back, for instance list
fusion. This is probably because there
-cafe@haskell.org
Subject: Re: [Haskell-cafe] Tutorial on Haskell
On 4/18/07, Taillefer, Troy (EXP) [EMAIL PROTECTED] wrote:
I have to strongly disagree with the statement that developers
like to
debug. Debugging is necessary because you can't reason about any
On 4/18/07, Taillefer, Troy (EXP) [EMAIL PROTECTED] wrote:
Sorry for the long rant but I get tired of people with their juvenile and
unconstructive statements like C++ sucks
Or Language X is better then Language Y even if it could ever be
objectively true (which I am sorry it can't be) who
As one who teaches programming in a lot of different languages, I can
state unequivocally that strong static typing of the Haskell or Ocaml
variety is (in addition to all its other benefits) a godsend to the
instructor. So many incorrect ways of writing programs are simply ruled
out right at
G'day all.
I wrote:
I think you could. What you need to convince a strict programmer of is
that laziness gives you modularity. The Graham Hutton Sudoku solver is
a nice example, but it'd be cool if we had a similar example that was
less cheesy than Sudoku.
OK, it's not pretty, but this is
In my opinion, one of the things that makes Haskell difficult to
learn is the value system. I'm not referring to pure vs.
impure. Instead, I am referring to the beliefs and principles held
by the Haskell community that are not shared with most of the
programming world. Principles like
R Hayes wrote:
They *enjoy* debugging ...
I have to say this is one of the best things I've found for catching
bad programmers during interviews, no matter what kind of system it is
for. I learned this the hard way after watching someone who never
really understood her program, but just kept
What would be really useful is a Haskell Cookbook that
shows how to do in Haskell things that are so easily
done in imperative languages. How to solve simultaneous
equations using Gaussian elimination comes to mind.
Lots of examples would be great.
Dave Feustel
On Apr 17, 2007, at 4:46 PM, David Brown wrote:
R Hayes wrote:
They *enjoy* debugging ...
I have to say this is one of the best things I've found for catching
bad programmers during interviews, no matter what kind of system it is
for. I learned this the hard way after watching someone
R Hayes wrote:
On Apr 17, 2007, at 4:46 PM, David Brown wrote:
R Hayes wrote:
They *enjoy* debugging ...
I have to say this is one of the best things I've found for catching
bad programmers during interviews, no matter what kind of system it is
for. I learned this the hard way after
Friends
I have agreed to give a 3-hr tutorial on Haskell at the Open Source Convention
2007
http://conferences.oreillynet.com/os2007/
I'm quite excited about this: it is a great opportunity to expose Haskell to a
bunch of smart folk, many of whom won't know much about Haskell. My
What about demonstrating the use of an Haskell interpreter as a pimped up
calculator?
multTable = putStr $ unlines [unlines [show x ++ ' ':show y ++ ' ':show
(x*y)|y-[1..10]] | x-[1..10]]
2007/4/16, Simon Peyton-Jones [EMAIL PROTECTED]:
Friends
I have agreed to give a 3-hr tutorial on
Give them a program that selects a bunch of files based on some
filtering criteria, and then does something to each file.
Kind of like find + xargs, but using haskell instead. Good recipe for sysadmins.
There was a recent example involving parsing raw emails into a thread here
On 16/04/07, Thomas Hartman [EMAIL PROTECTED] wrote:
Maybe that could be simplified and something could be based on that.
A one-liner using PCRE regex might also be of use.
Unless it can be performed with astounding dexterity, I don't think
try to beat, for example, Perl at its own game
There may be something to this point of view.
On the other hand, it is easier for me to see examples that can
connect back to something I am already familiar with.
That said, I will mention something where perl *seemed* to be a fit,
but later proved frustrating. To whit -- Doing something at
Well, given that concurrency is a hot topic at the moment, how about
something based on STM?
E.g. perhaps some kind of instant messaging server? Or Twitter except
scalable. By ruthlessly eliminating features, you could get the core of
one of these down to something that could be built in three
apart, as long as the
type checker agrees the pieces all fit back together, the program works
as i expect it to.
(Perhaps not so easy to apply this to a tutorial setting?)
-k
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On Mon, 2007-04-16 at 11:06 +0100, Dougal Stanton wrote:
A one-liner using PCRE regex might also be of use.
Unless it can be performed with astounding dexterity, I don't think
try to beat, for example, Perl at its own game will produce worthwhile
results.
One possibility is a task where
On 4/16/07, Ketil Malde [EMAIL PROTECTED] wrote:
On Mon, 2007-04-16 at 13:27 +0200, Thomas Hartman wrote:
To recap: transform a piece of simple code that works in serial, so it
works in parallel. Maybe even a couple, or three ways: using forks,
using threads, using map reduce.
This made me
On Mon, 2007-04-16 at 09:34 +0100, Simon Peyton-Jones wrote:
Friends
I have agreed to give a 3-hr tutorial on Haskell at the Open Source
Convention 2007
http://conferences.oreillynet.com/os2007/
I'm quite excited about this: it is a great opportunity to expose Haskell to
a
Hi
I think its important to cover whats different about Haskell. Things
like laziness are cool, but are harder to convince a strict programmer
that they are useful. Types however are obviously very handy, if you
can focus on why a Haskell program is so obviously correct easily.
1) the type
Hans van Thiel wrote:
On Mon, 2007-04-16 at 09:34 +0100, Simon Peyton-Jones wrote:
Friends
I have agreed to give a 3-hr tutorial on Haskell at the Open Source Convention
2007
http://conferences.oreillynet.com/os2007/
I'm quite excited about this: it is a great opportunity to expose
One technique I find compelling is (ab)using the type class system for
meta programming. Something from Lightweight Static Resources, Faking
It, or Hinze's Full Circle slides might be really attractive. Perhaps
Danvy's Haskell printf? The hook might be:
Yeah, you've heard of strong static typing
AM
To: haskell-cafe@haskell.org
Subject: [Haskell-cafe] Tutorial on Haskell
Friends
I have agreed to give a 3-hr tutorial on Haskell at the Open Source
Convention 2007
http://conferences.oreillynet.com/os2007/
I'm quite excited about this: it is a great opportunity to expose
Haskell
; haskell-cafe@haskell.org
| Subject: RE: [Haskell-cafe] Tutorial on Haskell
|
| Simon,
|
| Hopefully a video of this tutorial would be made available as a learning
| resource for those of use who can't make it to this Convention.
|
| Troy
|
|
| -Original Message-
| From: [EMAIL PROTECTED]
| [mailto
Neil Mitchell [EMAIL PROTECTED] writes:
(snip)
I think its important to cover whats different about Haskell. Things
like laziness are cool, but are harder to convince a strict programmer
that they are useful.
(snip)
Mmmm, it took me a while to really find laziness useful, and that was
normally
I found this blog post, which describes a way to protect against SQL
injection attacks using the type system, to be really enlightening.
http://blog.moertel.com/articles/2006/10/18/a-type-based-solution-to-the-strings-problem
Justin
___
Haskell-Cafe
Having just read Simon Marlow's paper on the Haskell Web Server, I
think it might be interesting to at least mention it, and how simple
it is, while still performing well.
Also, I second the comment several have made so far that talking
about concurrency is important. Haskell does it
Mark T.B. Carroll wrote:
I'm afraid no
examples come easily to mind, though.
Here's a simple one: reading a flattened graph from disk. If your
flattened representation contains forward references, you have to fix
them up in a strict language. In a lazy language, you can refer to
elements
Bryan O'Sullivan [EMAIL PROTECTED] writes:
Mark T.B. Carroll wrote:
I'm afraid no
examples come easily to mind, though.
Here's a simple one: reading a flattened graph from disk. If your
flattened representation contains forward references, you have to fix
them up in a strict language.
Neil Bartlett wrote:
E.g. perhaps some kind of instant messaging server? Or Twitter except
scalable.
A twitter-alike will quite probably get people's attention. And of
course anything that breaks the it's good for compilers! stereotype is
to be commended :-)
Also on the subject of
Mark T.B. Carroll wrote:
Bryan O'Sullivan [EMAIL PROTECTED] writes:
Mark T.B. Carroll wrote:
I'm afraid no
examples come easily to mind, though.
Here's a simple one: reading a flattened graph from disk. If your
flattened representation contains forward references, you have to fix
them up
Neil Mitchell wrote:
Things
like laziness are cool, but are harder to convince a strict programmer
that they are useful.
Strict programmers like the yield command too. The same behaviour can
be obtained by laziness, with easier reasoning.
That said, strict programmers may or may not like
Blast.. i didn't hit reply all so here's a forward of my mail to the
group...
--ryan
-- Forwarded message --
From: Ryan Dickie [EMAIL PROTECTED]
Date: Apr 16, 2007 4:24 PM
Subject: Re: [Haskell-cafe] Tutorial on Haskell
To: Simon Peyton-Jones [EMAIL PROTECTED]
I can tell you
G'day all.
Quoting Neil Mitchell [EMAIL PROTECTED]:
I think its important to cover whats different about Haskell. Things
like laziness are cool, but are harder to convince a strict programmer
that they are useful.
I think you could. What you need to convince a strict programmer of is
that
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