Lambda Days is a joint industry/academic conference on functional
programming, held annually at the Jagiellonian University in Krakow. Lambda
Days is calling both for proposed presentations, and for research papers,
the latter to be published after the event in Concurrency and Computation:
logy, Krakow, Poland
Katarzyna Rycerz, AGH University of Science and Technology, Krakow, Poland John
Hughes, Chalmers University of Technology, Gothenburg, Sweden Kevin Hammond,
University of St. Andrews, St. Andrews, Scotland, UK
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Lambda Days is a 2-day developer conference to be held in Krakow next year, Feb
26-27,
devoted to all things functional. Abstract submission is open until the 5th of
January.
http://www.lambdadays.org/
Last year’s program is available here:
http://www.lambdadays.org/lambdadays2014/#schedule
Why not adapt some cool Haskell ideas to Erlang too? Six weeks to go...
John Hughes
[http://www.erlang.org/workshop/2011/erlang090.gif]
CALL FOR PAPERS
Eleventh ACM SIGPLAN Erlang Workshop
Copenhagen, Denmark
Friday, September 14, 2012
[http://www.erlang.org/workshop/2011/acm_logo_wordmark.gif
(It would be nice to see some papers on Haskell automated testing here)
John
AST 2012
7th IEEE/ACM International Workshop on Automation of Software Test
http://ast2012.org
At ICSE 2012 (http://www.ifi.uzh.ch/icse2012/)
Zurich, Switzerland, 2-3 June 2012
IMPORTANT DATES:
Submission deadline:
We're recruiting Assistant Professors to the FP group for our new Strategic
Research project RAW FP. Come and work with us! Two-body problem? We've got
two jobs!
Deadline coming up on the 18th.
John Hughes
http://wiki.portal.chalmers.se/cse/pmwiki.php/FP/FP
https://site1.reachmee.com/I003
We're advertising a position for a PhD student in the FP group at Chalmers,
with closing date the 1st of September. Interested? Please apply!
http://www.chalmers.se/cse/EN/news/vacancies/positions/phd-student-position-in8107
John Hughes
via this
link:
http://www.chalmers.se/cse/EN/news/vacancies/positions/phd-student-position-in8107
Deadline for applications: 1st September.
John Hughes
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TAIC-PART is an interesting conference on testing that takes place in wonderful
surroundings in Windsor Park. I recommend it-I much enjoyed it last year. It's
calling for fast abstracts-short papers on new results-by June 11th. It would
be fun to see work on testing in the FP community
://www.cs.allegheny.edu/ast2010/
John Hughes
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of a presentation of up to 15 slides--so there's no excuse
for not putting something together!
So how about it? It would be great to see some Haskell papers at the workshop!
Deadline 20 January.
John Hughes
PS Check out the ICSE web site for information on the location:
http://www.sbs.co.za/ICSE2010
. To be eligible, you must have a doctorate from a
non-Swedish University. We will plan to interview suitable candidates.
The Chalmers Functional Programming group has as its senior members
John Hughes, Mary Sheeran, Koen Claessen, Patrik Jansson and Björn von
Sydow, as well as around 8 post-docs
Sweden
They need to arrive by Friday morning at the latest. Let me know by email to
expect them.
Its delightful to find that there are both job-seekers and employers enough
to make this kind of event a success!
John Hughes
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have many skilled functional programmers among our students, it
is of course open to anyone who would like to take part. All the details can
be found at www.jobs-in-fp.org.
Welcome to what promises to be a very exciting event!
John Hughes
Interested in recruiting Haskell programmers from Chalmers/Gothenburg
university? As an experiment, I am planning a recruitment event here in
December-see www.jobs-in-fp.org for how to take part.
John Hughes
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Haskell
.
The official announcement follows.
John Hughes
PhD Position in Functional Programming at the department of Computer Science
and Engineering
The Department provides strongly international and dynamic research
environments with 76 faculty and 55 PhD students from about 30 countries.
For more
Take a look at World Class Product Certification using Erlang by Ulf Wiger et
al. It's about a real project, not a scientific experiment, but even so it aims
to demonstrate some of the claims made for FP. It's Erlang, not Haskell, but
that doesn't really matter. The product is certainly a
to generate infinite random
data-structures with it.
John Hughes
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From: Robert Dockins [EMAIL PROTECTED]
It seems to me that every possible use of a partial function has
some (possibly imagined) program invariant that prevents it from
failing. Otherwise it is downright wrong. 'head',
'fromJust' and friends don't do anything to put that invariant in
I propose that haskell' include a standard syntax for invariants that
the programmer wants to express.
The intent is not to have standardized checks on the invariants, its
just to supply a common way to specify invariants to that the various
strategies for checking them can all work from the
What I implemented in GHC is an extension of the proposal below. The
proposal just mentions:
deriving Class for Type
In GHC I also added a form for newtype deriving of multi-parameter
type classes:
deriving (Class t1 ... tn) for Type
I think that it's close to what we
The intention is to put the speaker's slides online. But in some cases, that
will require additional permission from the company concerned--putting
slides on the web is more public than talking at a workshop. So some
sanitation may perhaps be needed. All this is going to take a little while,
On 9/6/06, Tamas K Papp [EMAIL PROTECTED] wrote:
or does the compiler perform this optimization? More generally, if a
function is invoked with the same parameters again (and it doesn't
involve anything like monads), does does it makes sense
(performancewise) to store the result somewhere?
John Hughes wrote:
The trouble is that this isn't always an optimisation. Try these two
programs:
powerset [] = [[]]
powerset (x:xs) = powerset xs++map (x:) (powerset xs)
and
powerset [] = [[]]
powerset (x:xs) = pxs++map (x:) pxs
where pxs = powerset xs
Try computing length (powerset [1..n
From: Julien Oster [EMAIL PROTECTED]
Subject: [Haskell-cafe] Exercise in point free-style
I was just doing Exercise 7.1 of Hal Daumé's very good Yet Another
Haskell Tutorial. It consists of 5 short functions which are to be
converted into point-free style (if possible).
It's insightful and
On 8/28/06, John Hughes [EMAIL PROTECTED] wrote:
No, map was never overloaded--it was list comprehensions that were
overloaded as monad comprehensions in Haskell 1.4. That certainly did
lead
to problems of exactly the sort John M is describing.
I just checked the reports for Haskell 1.3
From: Jon Fairbairn [EMAIL PROTECTED]
To
reinforce what Aaron said, if a programme works now, it'll
still work if map suddenly means fmap.
Well, this isn't quite true, is it? Here's an example:
class Foldable f where
fold :: (a - a - a) - a - f a - a
instance Foldable [] where
fold =
From: Jon Fairbairn [EMAIL PROTECTED]
To
reinforce what Aaron said, if a programme works now, it'll
still work if map suddenly means fmap.
Well, this isn't quite true, is it? Here's an example:
class Foldable f where
fold :: (a - a - a) - a - f a - a
instance Foldable [] where
fold =
Stephanie wrote:
Simon,
Why is an Appendix is better than just a footnote in the Standard that
says we aren't sure, one way or the other, whether FDs will stay in
the language for ever. Why do we need this extra structure?
I'm worried that this extra structure could be confusing. In
Dusan Kolar wrote:
Malcolm Wallace wrote:
Paul Johnson [EMAIL PROTECTED] wrote:
Is there a market that is poorly served by the incumbent languages for
which Haskell would be an absolute godsend?
Yes. Safety critical systems, encompassing everything from avionics to
railway
With a view to this I started collecting just the announcements on a
`feed' here:
http://www.cse.unsw.edu.au/~dons/code/hwn/announce.html
These should serve as a basis for the content, I think.
Can you add an actual date? Seeing things dated a few days ago does
contribute to a
Am Samstag, 4. März 2006 21:30 schrieb Neil Mitchell:
And a related question is: Which packages are searchable by Hoogle?
The best answer to that is some. I intentionally excluded OpenGL and
other graphics ones because they have a large interface and yet are
not used by most people
29% Parsec
19% wxHaskell
16% QuickCheck
16% haddock
12% Monadic Parser Combinators
11% Gtk2Hs
9% hs-plugins
8% HaXml
7% Data.*
7% Monad foundation classes
6% Arrows
6% HOpenGL
The list includes all libraries named by more than 5% of respondents.
Sure enough, wxHaskell and Gtk2Hs
From: Claus Reinke [EMAIL PROTECTED]
let's go through 5.2 Export Lists to see what would be missing
if we tried to replace the export list with a separation of a module
into a public (exported) and a private (local) part:
...
any other issues I missed here?
I feel unkeen.
One
Simon Peyton-Jones wrote:
I've updated the Wiki to add your strict proposal, but rather briefly.
If you want to add stuff, send it to me and I'll add it.
Meanwhile:
| And as a consequence, it is no longer possible to transform a pair of
| bindings into a binding of a pair. In Haskell 98,
|
|
On 2/5/06, Jim Apple [EMAIL PROTECTED] wrote:
Have we considered Restricted Data Types?
http://www.cs.chalmers.se/~rjmh/Papers/restricted-datatypes.ps
Nice to see my old paper hasn't sunk without trace!
As Taral pointed out, though, Restricted Data Types have not been implemented,
and
From: Ross Paterson [EMAIL PROTECTED]
John Hughes wrote:
I would urge that either we stick with the present design, or, if bang
patterns are added (which a lot speaks for), that the language be
simplified at the same time so that patterns are matched in the same way
everywhere
From: John Meacham [EMAIL PROTECTED]
Subject: Re: Restricted Data Types
however, what prevents the following from being _infered_
return Foo :: Moand m = m Foo
so, we think we can specialize it to
return Foo :: Set Foo
however, we no longer have the constraint that Foo must be in Eq!
Maybe
From: Ben Rudiak-Gould [EMAIL PROTECTED]
Subject: Re: Bang patterns, ~ patterns, and lazy let
It's also not that case that !x has the same
meaning in both proposals, e.g.
let { !x = y ; !y = const 'a' x } in x
means 'a' in the current proposal but _|_ in yours.
Aargh,
. The survey is now closed, and the results are available on the web
at http://www.cs.chalmers.se/~rjmh/Wash/Survey/teaching.htm. I've put up
the raw data, together with various simple analyses.
Enjoy!
John Hughes
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Quoting Paul Hudak [EMAIL PROTECTED]:
Actually, one of the main reasons that we chose (:) is that that's what
Miranda used. So, at the time at least, it was not entirely clear what
the de facto universal inter-language standard was.
Phil Wadler argued for the ML convention at the time,
Lennart Augustsson wrote:
I now think :: for type signatures was a bad mistake.
I don't use lists very much. They are not the right data structure
for many things. So : is not as common as :: in my code.
I checked a small sample of code, about 2 lines of Haskell.
It has about 1000
Cale Gibbard wrote:
That said, I'd *really* like to see monad comprehensions come back,
since they align better with the view that monads are container types,
dual to the view that monads are computations, which is supported by
the do-syntax. This view is actually much easier to teach (in my
I noticed ticket #55--add parallel list comprehensions--which according to
the ticket, will probably be adopted. I would argue against.
Firstly: because in its more general forms the notation is confusing. Try
this example:
[(i,j,k) | i-[1..3], j-[1..3] | k - [1..9]]
In general it's hard to
For the last few days, my mail-box has been full of mail about the M-R,
lazy pattern
matching, n+k patterns, comment syntax--it's just like the good old
days! And that
worries me.
Each of these topics is a snake pit--a tricky area of language design,
with many
alternative possibilities and no
Personally I think ~ patterns are great, and we are now talking about !
patterns, a kind of dual to ~ patterns. So at least I think we should
un-couple the two discussions.
I think so too. Removing ~ patterns seems like a fairly poor idea to
me. Sure, they're not very much explicitly
- Original Message -
From: Jake Luck [EMAIL PROTECTED]
To: haskell@haskell.org
Sent: Friday, January 27, 2006 7:41 AM
Subject: Re: [Haskell] Discrete event simulation
Part of this will be some kind of synchronisation primitive. I don't
much care what it is, but somewhere I need a
Ross Paterson wrote:
I suggest = for bind-by-name, and
:= for bind-by-need.
...
You're proposing that the =/:= distinction both decides whether
constrained type variables are monomorphic and whether the binding
should be implemented using sharing. If it only did the former (and the
--
Message: 1
Date: Wed, 21 Dec 2005 10:48:08 +
From: Robin Green [EMAIL PROTECTED]
Subject: Re: [Haskell-cafe] Re: Tutorial uploaded
Beginners should start with non-monadic functions in order to later avoid
IO
I would
appreciate it if you could help me by informing colleagues who are using
Haskell about the existence
of the survey.
The information gathered will be used in the History of Haskell paper
that I, Simon PJ, Phil Wadler
and Paul Hudak are working on.
Thanks very much for you help!
John
Wolfgang Jeltsch wrote:
Am Montag, 28. November 2005 16:39 schrieb John Hughes:
I'm carrying out another survey of the Haskell community, this time to
find out how Haskell is being used in university teaching.
Roughly how many students took the course last time it was taught?
What
Wolfgang Jeltsch wrote:
What is the first programming language students on your degree programme
learn?
What is the second programming language students on your degree programme
learn?
This is too restrictive. What if the lecture Computer Science I is held in
different years by different
Subject: Re: [Haskell] Haskell users survey--please respond!
Hello,
why doesn't the section about Haskell tools and libraries mention
HToolkit?
Best wishes,
Wolfgang
Because you haven't added it!
The survey is designed so that each respondent can add NEW favourite tools
to the list,
I want to stress that I'm interested in responses from ALL users--if
you're
a complete beginner writing your first Haskell programs on a course, I'd
like to know that, just as if you're one of the designers using it for
your next POPL article.
Do you also want respones from people which once
Am Mittwoch, 9. November 2005 13:09 schrieben Sie:
On Wed, Nov 09, 2005 at 01:02:19PM +0100, Wolfgang Jeltsch wrote:
Only 2% find fglasgow-exts useful???
Only 2% consider it a tool or library.
I think that if John cares about getting reliable results, he should
take the results from this
to complete. Please help by doing so! As a reward,
you'll get to see a summary of the responses so far.
The survey is at this URL:
http://www.cs.chalmers.se/~rjmh/Wash/Survey/Survey.cgi
Thanks for your help! I'll post a summary of the results to the list.
John Hughes
the mark!)
John
On 09/11/05, Sebastian Sylvan [EMAIL PROTECTED] wrote:
On 11/9/05, Fraser Wilson [EMAIL PROTECTED] wrote:
On 11/9/05, Aaron Denney [EMAIL PROTECTED] wrote:
On 2005-11-09, John Hughes [EMAIL PROTECTED] wrote:
The survey is at this URL:
http
Tomasz Zielonka wrote:
On Wed, Nov 09, 2005 at 04:55:46AM -0500, Cale Gibbard wrote:
It seems that if you keep trying to fill out the form, you will
eventually succeed. If someone finishes filling out the form between
when you start filling it out and when you finish, then the
Tomasz Zielonka wrote:
The tools list is extended automatically, after a response? There is an
odd entry Parsec, HOpenGL
Someone hasn't read the instructions :-)
BTW, is there a way to update my entry? I forgot to mention one of the
best tools I use - Parsec :-(
I'm afraid not,
at the workshop itself.
John Hughes and Peter Dybjer (session organisers)
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a very one-sided view, ignoring the large effect that
ease of programming can have on the final system's performance.
John Hughes
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in 1999. Here's the link:
http://www.cs.chalmers.se/~rjmh/Papers/restricted-datatypes.ps
Getting the right dictionaries to the right place involves adding a
concept of well-formed types, which perhaps is why it hasn't been taken
up by the Simons...
John Hughes
Message: 9
Date: Mon, 7 Feb 2005 10:31:30 -0500
From: Jacques Carette [EMAIL PROTECTED]
Subject: [Haskell-cafe] Top 20 ``things'' to know in Haskell
To: haskell-cafe@haskell.org
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain; charset=us-ascii
The recent post of Graham Klyne (below)
Lennart Augustsson and Thomas Johnsson got some encouraging results
fifteen years ago with their nu-G-machine. They compiled Lazy ML for a
shared memory multiprocessor, and benchmarked against the sequential LML
compiler, the precursor of hbc and at that time the best compiler for a
lazy
I seriously considered switching frlom Hugs to GHC for my introductory
programming class this year, but in the end stayed with Hugs because of
a single feature.
I'm teaching beginning programmers, and for them at least, there is an
overwhelming volume of names to learn -- what's that function?
. It's a function in the standard
library Directory, documented here:
http://haskell.org/onlinereport/directory.html
getDirectoryContents :: FilePath - IO [FilePath]
A FilePath is just a String.
John Hughes
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this in Haskell?
Just a supplement to my previous message: you can find better
documentation of the Directory library here:
http://www.haskell.org/ghc/docs/latest/html/libraries/base/System.Directory.html
John Hughes
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System.IO.Unsafe.
That will delay its evaluation until rs is evaluated, once again AFTER
the enclosing call has returned. But that is -- well -- unsafe.
John Hughes
PS You can read about lazy state here:
http://portal.acm.org/citation.cfm?id=178246coll=portaldl=ACMCFID=22769016CFTOKEN=85305111
| Constraints on datatype declarations are a misfeature of Haskell, and
| have no useful effect.
|
| Is this the final conclusion?
Yes, it is, I believe. Constraints on data type declarations are a
mis-feature. I tried to get them removed, but there was some argument
that they could be made
Adrian Hey wrote:
On Monday 29 Mar 2004 3:49 pm, John Hughes wrote:
Actually the cache behaviour of code generated by GHC isn't at all bad.
I know because I ran a student project a couple of years ago to
implement cache-friendly optimisations. The first thing they did was
cache
Adrian Hey wrote:
On Friday 26 Mar 2004 10:39 pm, Sean E. Russell wrote:
Why is Ocaml so darned fast compared to Haskell?
...
Also, I have a hunch that not only is eager evaluation inherently
more efficient (in terms of the raw number of operations that need
to be performed), it's
Robert Will wrote:
4.
A notation for preconditions. For simple functions a Precondition
can be calculated automatically from the Patterns:
head (x:xs) = x
Gives the Precondition @xs /= []@ for @head [EMAIL PROTECTED] This only needs
some simple knowledge
recognise that.
Incidentally, exactly the same problem arises for functions: Haskell does
not have true functions either, because _|_ and \x - _|_ are not equal.
John Hughes
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.
That said, maybe it is surprising that no good Haskell pretty-printer has
appeared yet, especially given the importance of layout in the language.
Why not write one? I dare say there would be many users, and no doubt you
could publish a paper at the Haskell Workshop...
John Hughes
On Fri, 5 Sep 2003, Simon Marlow wrote:
... Claiming a lock on a file is
easy in C (well,
it takes 18 lines...), but there's nothing in the standard Haskell
libraries that can do it. So I borrowed a little C code from
the net, and
called it via the FFI.
Locking support is available
On Thu, 4 Sep 2003, Sebastian Sylvan wrote:
On Thu, 4 Sep 2003, John Hughes wrote:
I wrote the system for my (Haskell!) programming course, with 170 students
last year, and it is now also being used (at least) for our Java course
and a cryptography course. It consists of about 600 lines
On Fri, 5 Sep 2003, Johannes Waldmann wrote:
On Thu, 4 Sep 2003, John Hughes wrote:
I use Haskell and Wash/CGI for administering students lab work.
same here (in addition to Haskell programs for actually grading the homework).
just curious: what kind of data base do you use?
we take
) for our Java course
and a cryptography course. It consists of about 600 lines of Haskell and
18 lines of C.
John Hughes
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to fund this work. The project leaders are John
Hughes, Mary Sheeran, Peter Dybjer, and Thierry Coquand.
We are looking for well qualified candidates with a recent doctorate
in a related area, and with proven system building skills, to spend up
to two years with us as Research Fellows. We are looking
- Great care should be exercised in the use of this function. Not only
- because of the danger of introducing side effects, but also because
- \code{unsafePerformIO} may compromise typing, for example, when it is used
- in conjunction with polymorphic references.
Or maybe it
()
John Hughes
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Haskell against ... which often leads them to become real Haskell
enthusiasts! But then again, my course emphasises real programming and
real-world problem solving, at the expense of logic and induction.
John Hughes
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On Thu, 16 Jan 2003, Hal Daume III wrote:
I have a function which behaves like map, except instead of applying the
given function to, say, the element at position 5, it applies it to the
entire list *without* the element at position 5. An implementation looks
like:
mapWithout :: ([a] - b)
, in the
hugs interpreter -- my tools only need to know how to work the hugs
interface. As the language evolves, I can keep up just by installing a
new version of hugs -- I have no parser and interpreter of my own to
maintain.
Easy and effective -- if a bit slow.
John Hughes
On Mon, 2 Dec 2002, Andrew J Bromage wrote:
... If you mention a term like design patterns,
well I love design patterns, it's just that in Haskell-land
they are called higher-order functions, or polymorphic functions, etc.
-- Johannes Waldmann
On Tue, 3 Dec 2002, Andrew J Bromage wrote:
On Mon, Dec 02, 2002 at 10:27:21AM +0100, John Hughes wrote:
There are patterns of that sort in our programs, which we would probably
rather call design techniques, which aren't so easily captured by a
higher-order function definition
What does nub stand for? (This is the first I've heard of it.)
From the definition in List.hs it seems to remove repeats, keeping
only the first.
Yes, that's what it does. It doesn't stand for anything, it's a word:
nub: small knob or lump, esp. of coal; small residue, stub; point or gist
be deferred in
the way I describe.
If I remember rightly, OCaml allows type recursion of this sort, but
restricts it to object types precisely to avoid these problems.
John Hughes
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On Fri, 7 Jun 2002, Chris Moline wrote:
...
two. i have also read what the hell are monads and monads for the working
haskell programmer. i still do not get what i am doing wrong.
getDepends :: String - [String]
getDepends p = do
handle - openFile (portsDir ++ p ++ /+CONTENTS)
monadic do,
you name the values entered into input fields at the time you create the
fields, and you supply a call-back function for the submit button. That's
it.
John Hughes
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On Sat, 25 May 2002, Koen Claessen wrote:
There are many types which would fit nicely in an arrow
framework, but do not because of the demand of these
operators, here are two examples:
* Isomorphisms, are nice arrows:
type Iso a b = (a - b, b - a)
but of course not all
On Fri, 24 May 2002, Tom Schrijvers wrote:
The first result for nub in dictionary.com gives:
nub Pronunciation Key (nb)
n.
1. A protuberance or knob.
2. A small lump.
3. The essence; the core: the nub of a story
I think essence is the right meaning, removing all duplicates.
Cheers,
(galois.com), although I know there are others. Funny there's no Haskell
in Industry section on haskell.org -- it might be small, but it wouldn't
be empty, if people using Haskell were willing to stand up and be counted.
John Hughes
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)))
where if you substitute for fac before applying the lambda-expression, you
clearly fall into a loop.
John Hughes
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own program.
John Hughes
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Why can I not define the following (in ghc):
class Foo p where
instance Foo Double where
foo :: Double - (forall q . Foo q = q)
foo p = p
From my humble (lack of) knowledge, there seems to be nothing wrong
here, but ghc (5.03)
Why can I not define the following (in ghc):
class Foo p where
instance Foo Double where
foo :: Double - (forall q . Foo q = q)
foo p = p
From my humble (lack of) knowledge, there seems to be nothing wrong
here, but ghc (5.03)
I think the point that's being missed in this discussion
is that a monad is a n *abstract* type, and sometimes the
natural equality on the abstract type is not the same as
equality on representations. ... If we can give a more efficient
them. For the *language* to rule out constructing
different representations for equivalent constructions, such as and =,
would be unreasonable.
John Hughes
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