One solution would be to fold over a specific semigroup instead of a
recursive function:
|import Data.Semigroup
import Data.Foldable(foldMap)
import Data.Maybe(maybeToList)
data Darle a =Darle {getInit :: [a],getLast ::a }
deriving Show
instance Semigroup (Darle a)where
On Thu, Aug 29, 2013 at 9:30 PM, Mateusz Kowalczyk
fuuze...@fuuzetsu.co.ukwrote:
Greetings café,
Perhaps some saddening news for Markdown fans out there. As you might
remember, there was a fair amount of push for having Markdown as an
alternate syntax for Haddock.
This is a little
Is there an up todate copy of the haddock manual online anywhere?
On Saturday, August 31, 2013, Omari Norman wrote:
On Thu, Aug 29, 2013 at 9:30 PM, Mateusz Kowalczyk
fuuze...@fuuzetsu.co.uk javascript:_e({}, 'cvml',
'fuuze...@fuuzetsu.co.uk'); wrote:
Greetings café,
Perhaps some
Great package!
One question: Do you remove/inline type synonyms? I ask because I just ran into
this with some TH code. I'm looking for types that end with - a, but that
fails when type synonyms are involved.
Sjoerd
On Aug 30, 2013, at 2:08 AM, Richard Eisenberg e...@cis.upenn.edu wrote:
On 31/08/13 16:20, Carter Schonwald wrote:
Is there an up todate copy of the haddock manual online anywhere?
No. You can build your own documentation. In Haddock directory, go into
‘doc’ and read the README on how to build it. That is also outdated
however: for example, it doesn't provide
Hello,
I disagree.
While none of your detail points are wrong, they mainly focus on the
fact that there is no 1-to-1 mapping between the existing haddock markup
and Markdown. I don't think there needs to be. If Markdown can do
something new, that something can be added; if something doesn't make
On 31/08/13 19:14, Niklas Hambüchen wrote:
Hello,
I disagree.
That's fine, that's why the thread is here.
While none of your detail points are wrong, they mainly focus on the
fact that there is no 1-to-1 mapping between the existing haddock markup
and Markdown. I don't think there needs
Hi. I was just curious about something. In one of my math textbooks I
see expressions like this
f + g
or
(f + g)(a)
where f and g are functions. What is meant is
f(a) + g(a)
Is there a way in Haskell you can make use of syntax like that (i.e.,
expressions like f + g and f * g to create a
* Thiago Negri evoh...@gmail.com [2013-08-29 22:27:47-0300]
I can't install tasty with cabal. Anyone with the same issue or a fix?
$ cabal install tasty
...
Test\Tasty\Core.hs:147:11: Not in scope: `witness'
You probably have a too old version of 'tagged'. I'll add the lower
version bound
Suppose I need to get an element from a data structure, and also
modify the data structure. For example, I might need to get and delete
the last element of a list:
darle xs = ((last xs), (rmlast xs)) where
rmlast [_] = []
rmlast (y:ys) = y:(rmlast ys)
There are probably other and better ways
isn't this what zippers are for?
b
On Aug 30, 2013, at 1:04 PM, Clark Gaebel wrote:
I don't think a really smart compiler can make that transformation. It looks
like an exponential-time algorithm would be required, but I can't prove that.
GHC definitely won't...
For this specific
I don't think a really smart compiler can make that transformation. It
looks like an exponential-time algorithm would be required, but I can't
prove that.
GHC definitely won't...
For this specific example, though, I'd probably do:
darle :: [a] - (a, [a])
darle xs =
case reverse xs of
[]
Hi,
On 28/08/13 21:05, Wvv wrote:
Let we have data in one module as this:
data Person = Person { personId :: Int, name :: String }
data Address a = Address { personId :: Int, address :: String , way ::
a}
It was discussed a lot in topics OverloadedRecordFields
This is
Hi,
Thank you for the reply.
Unlikely it is the case (if I understand it correctly). The exception is
thrown by enumSocket, I added traces to prove that. And it is
propagated to
runWithSocket (
Hi,
Isn't it by design? Consider the next code:
import Data.Enumerator (($$), (==))
import qualified Data.Enumerator as E
import qualified Data.Enumerator.List as EL
import Control.Exception
import Control.Monad.IO.Class
main :: IO ()
main = do
res - E.run $ myEnum $$
EL.take 5
Hi,
I am positive about the following situation, but I can't find any
concrete answer on the Web. Can anyone confirm this ?
In template-haskell-2.7.0, the following quote
[t| () |]
appears as a (ConT name), where name is the name for unit. However,
in template-haskell-2.8.0, the same quote
I can't answer about expected behavior, but I can say that those two
constructions should be considered identical by the $(…) splice construct. For
better or worse, Template Haskell often offers multiple ways of encoding the
same source Haskell phrase, and any code that processes Template
Hi,
Cabal 1.18 is still in the release candidate stage so it has in fact not
been released yet. We could either bump the dependency on base to 4.8
before the 1.8 release or we could make a Cabal-1.8.0.1 release together
with the GHC release that bumps the dependency.
-- Johan
On Wed, Aug 28,
I can't answer about expected behavior, but I can say that those
two constructions should be considered identical by the $(…) splice
construct. For better or worse, Template Haskell often offers
multiple ways of encoding the same source Haskell phrase, and any
code that processes Template
Hi Jose and Richard,
haskell-src-meta has Language.Haskell.Meta.Utils.normalizeT which can
help with making code treat the two constructs equivalently, though
I imagine using th-desugar instead will make that process harder to
mess up.
Adam
On Thu, Aug 29, 2013 at 10:13 AM, Richard Eisenberg
I've always considered Unit to just be a nullary tuple. This intuition has
never steered me wrong, and it seems that Template Haskell is making the same
assumption. If there's some reason that this conflation of ideas is wrong, I
would be eager to know -- th-desugar makes this assumption in
Hello.
While hacking in one of my projects, one of my modules stopped to compile
for apparently no reason. The compiler just freezes (like if it where in an
infinite loop) while trying to compile that particular module. Since I had
this problem I have been trying to reduce the problem as much as
On Thu, Aug 29, 2013 at 12:08 PM, Daniel Díaz Casanueva
dhelta.d...@gmail.com wrote:
Since this problem can be OS-dependent, my system is Debian 7 and I didn't
try yet to reproduce my problem in other systems (mainly because I don't
have access to other systems at the moment).
FWIW, it’s not
This is a known GHC bug that (i believe?) is fixed in head. Links to the
relevant tickets from when I hit this problem trying to build lambdabot are
here https://github.com/mokus0/random-fu/issues/13
The work around is to build those libraries with -O1
On Thu, Aug 29, 2013 at 1:00 PM, Manuel
Hi all!
(in case you don't read /r/haskell : ))
Stephen Blackheath and I are extremely happy to report that as of today,
GHC can natively build binaries for iOS devices and the iOS Simulator.
You'll find everything you need here:
http://ghc.haskell.org/trac/ghc/wiki/Building/CrossCompiling/iOS
Stephen provided some more credits — thanks so much to all!
Three connected projects concerning cross-compilation:
*Registerised ARM support, added using David Terei's LLVM compiler back end
with Stephen Blackheath doing an initial ARMv5 version and LLVM patch and
Karel Gardas working on
OK
I have a bunch of BSON documents that I convert to ByteStrings, put in a
Map, and write to a socket based on the response. I noticed some high
memory usage (in the GBs) so I decided to investigate. I simplified my
problem into a small program that demonstrates clearer what is happening.
I
A good starting point is to estimate how much space you think the data
should take using e.g.
http://blog.johantibell.com/2011/06/memory-footprints-of-some-common-data.html
If you do that, is the actual space usage close to what you expected?
On Thu, Aug 29, 2013 at 5:35 PM, Kyle Hanson
I've just uploaded my new th-desugar package, which enables easier processing
of Template Haskell source syntax by desugaring it into a much simpler core
language. The meaning of the code after desugaring is identical to before
desugaring, but the syntax is much simpler. To wit, th-desugar
On 30/08/2013, at 2:38 AM, Daniel Díaz Casanueva wrote:
While hacking in one of my projects, one of my modules stopped to compile for
apparently no reason. The compiler just freezes (like if it where in an
infinite loop) while trying to compile that particular module. Since I had
this
I can't install tasty with cabal. Anyone with the same issue or a fix?
$ cabal install tasty
...
Test\Tasty\Core.hs:147:11: Not in scope: `witness'
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Greetings café,
Perhaps some saddening news for Markdown fans out there. As you might
remember, there was a fair amount of push for having Markdown as an
alternate syntax for Haddock.
Unfortunately, this is probably not going to happen for reasons listed
on the post I just published at [1].
Building a map with foldr seems unwise, have you tried doing it with
fromListWith instead? Or foldl'? In either case, since you don't even put
the map into WHNF, none of the computation is done at all in either case
until the first lookup.
On Thu, Aug 29, 2013 at 3:35 PM, Kyle Hanson
Thanks Bob,
I made it foldr because it was meant to simulate the sequential IO action
that my server uses to populate the Map.
I found the problem to be that I need to force the map to evaluate so
adding a little $! fixed the problem
--
Kyle Hanson
On Thu, Aug 29, 2013 at 9:09 PM, Bob
foldl' is the right way to simulate the sequential IO action, foldr would
be doing it in reverse (and for large enough input will stack overflow).
On Thu, Aug 29, 2013 at 9:33 PM, Kyle Hanson hanoo...@gmail.com wrote:
Thanks Bob,
I made it foldr because it was meant to simulate the
On Tue, 27 Aug 2013, John Lato wrote:
[1] Most people are physically incapable of reading documents that explain why
what they want to do won't
work. Even if people did read the documentation, I suspect that the people
most in need of the information
would be the least likely to understand
On 27 Aug 2013, at 08:33, Niklas Hambüchen wrote:
@Malcolm, would you mind a change towards throwing an exception that is
different from error so that it can be easily caught, or even better, a
change from
runCpphs :: ... - IO String
to
runCpphs :: ... - IO (Either String
Let we have data in one module as this:
data Person = Person { personId :: Int, name :: String }
data Address a = Address { personId :: Int, address :: String , way ::
a}
It was discussed a lot in topics OverloadedRecordFields
This is an alternative:
Let we have polymorphic
On 29/08/13 00:43, Malcolm Wallace wrote:
Have you tried simply wrapping the call to runCpphs in a catch? Something
like
safeRunCpphs :: ... - IO (Either String String)
safeRunCpphs foo = fmap Right (runCpphs foo) `catch` (\(UserError s)-
Left s
Yes, that is what I'm doing at
Welcome to issue 278 of the HWN, an issue covering crowd-sourced bits
of information about Haskell from around the web. This issue covers the
week of August 18 to 24, 2013.
Quotes of the Week
* johnw: finger trees must be related to palm trees somehow
* monochrom: do, or undo. there is no
Greetings café,
There are some problems in Haddock to do with Template Haskell that I
believe are being caused by Cabal. These were apparently addressed in
1.18 which came out recently. ‘Great!’, I thought.
My problem is that I'm unsure how to use 1.18. I'm using GHC HEAD (well,
3 days old now)
Thanks for your examples.
On 27/08/13 13:59, Albert Y. C. Lai wrote:
The correct fix is to raise the stack cap, not to avoid using the stack.
Indeed, ghci raises the stack cap so high I still haven't fathomed where
it is. This is why you haven't seen a stack overflow in ghci for a long
Hi,
Is it possible to retrieve all definitions contained in a module using
Template Haskell ?
Thanks,
Jose
--
Jose Antonio Lopes
Ganeti Engineering
Google Germany GmbH
Dienerstr. 12, 80331, München
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
Geschäftsführer:
See http://ghc.haskell.org/trac/ghc/wiki/DefaultSuperclassInstances
| -Original Message-
| From: Haskell-Cafe [mailto:haskell-cafe-boun...@haskell.org] On Behalf
| Of Henning Thielemann
| Sent: 26 August 2013 20:07
| To: Frantisek Farka
| Cc: Haskell Cafe
| Subject: Re: [Haskell-cafe]
Hi,
after some debugging of a higher-level tool I found out that when I use
cpphs as a library and the `runCpphs` function that is to produce the
preprocessed output, when it comes across the #error directive it will
terminate my program.
This is because handling #error is implemented with
Hi Jose,
Template Haskell doesn't parse code.
haskell-src-exts and the GHC API can do that.
Have a look at:
* ghc-mod browse (using ghc api)
* hscope (using haskell-src-exts)
On 27/08/13 15:45, Jose A. Lopes wrote:
Hi,
Is it possible to retrieve all definitions contained in a module using
Thanks,
Jose
--
Jose Antonio Lopes
Ganeti Engineering
Google Germany GmbH
Dienerstr. 12, 80331, München
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
Geschäftsführer: Graham Law, Christine Elizabeth Flores
Steuernummer: 48/725/00206
On Mon, Aug 26, 2013 at 4:46 AM, Niklas Hambüchen m...@nh2.me wrote:
On #haskell we recently had a discussion about the following:
import System.Random
list - replicateM 100 randomIO :: IO [Int]
I would think that this gives us a list of a million random Ints. In
fact, this is
On 27/08/13 20:37, Patrick Palka wrote:
You can use ContT to force the function to use heap instead of stack
space, e.g. runContT (replicateM 100 (lift randomIO)) return
That is interesting, and works.
Unfortunately its pure existence will not fix sequence, mapM etc. in base.
On Mon, Aug 26, 2013 at 12:05:14PM -0700, Bryan O'Sullivan wrote:
On Mon, Aug 26, 2013 at 1:46 AM, Niklas Hambüchen m...@nh2.me wrote:
This is because sequence is implemented as
sequence (m:ms) = do x - m
xs - sequence ms
return
Hello,
I'm debugging an issue in websockets package,
https://github.com/jaspervdj/websockets/issues/42
I'm not familiar with enumerator package (websockets are based on it),
so I'm looking for help. The exception is throws inside enumSocket
enumerator using
throwError (
This is partially guesswork, but the code to catchWSError looks dubious:
catchWsError :: WebSockets p a
- (SomeException - WebSockets p a) -
WebSockets p a catchWsError act c = WebSockets $ do env - ask
let it = peelWebSockets env $ act cit =
adam vogt wrote:
TH quotes limited as you've noticed. One way to generate similar code
is to note that:
do
let x = y
z
is the same as let x = y in do z. You can generate the latter with
something like the following file, but the `a' isn't in scope for the
second argument to
IMHO it's perfectly reasonable to expect sequence/replicateM/mapM to be
able to handle a list of ~1e6 elements in the Unescapable Monad (i.e. IO).
All the alternate implementations in the world won't be as handy as
Prelude.sequence, and no amount of documentation will prevent people from
running
Michael Snoyman wrote:
You can build this up using the = operator[1] in stm-conduit, something
like:
eitherSrc :: MonadResourceBase m
= Source (ResourceT m) a - Source (ResourceT m) b - Source
(ResourceT m) (Either a b)
eitherSrc src1 src2 = do
join $ lift $
Hi Nicolas,
It's not intentional, but Iavor is aware of this, and we want to change it.
I'm CC-ing him as he might know more about what the current plan is.
Cheers,
Pedro
On Sat, Aug 24, 2013 at 3:20 PM, Nicolas Trangez nico...@incubaid.comwrote:
Hello Cafe,
I was playing around with
On #haskell we recently had a discussion about the following:
import System.Random
list - replicateM 100 randomIO :: IO [Int]
I would think that this gives us a list of a million random Ints. In
fact, this is what happens in ghci. But with ghc we get:
Stack space overflow: current
As an example that this actually makes problems in production code, I
found this in the wildlife:
https://github.com/ndmitchell/shake/blob/e0e0a43/Development/Shake/Database.hs#L394
-- Do not use a forM here as you use too much stack space
bad - (\f - foldM f [] (Map.toList status)) $
Problem solved: with mate, use atril instead of evince.
(I think it is a gtk2/tgk3 issue and it's got nothing to do with xmonad.)
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On 14/07/13 20:20, Niklas Hambüchen wrote:
As you might not know, almost *all* practical Haskell projects use it,
and that in places where an Ord instance is given, e.g. happy, Xmonad,
ghc-mod, Agda, darcs, QuickCheck, yesod, shake, Cabal, haddock, and 600
more (see
He-chien Tsai wrote:
I'm sick for checking whether package is obsolete or not.
I think packages build failed long time ago should be collected and moved
to another page until someone fix them, or hackage pages should have a
filter for checking obsolete packages.
People are working on it.
Hi guys,
Yep, we know about this and, I believe, the plan is to add custom rules to
the constraint solver to solve `Typable n` constraints (where n is a
number or symbol). Just for the record, the other design choice was to
add instance `Typeable (n :: Symbol)`, but that conflicted with some
On Mon, Aug 26, 2013 at 1:46 AM, Niklas Hambüchen m...@nh2.me wrote:
This is because sequence is implemented as
sequence (m:ms) = do x - m
xs - sequence ms
return (x:xs)
and uses stack space when used on some [IO a].
This problem
The problem of refinement of type classes annoys me from time to time
when I work on the NumericPrelude. It is an experimental type class
hierarchy for mathematical types. Sometimes a new data type T shall be
implemented and it turns out that you can implement only a part of all
methods of
I've always stuck to the definition of a closed lambda term (the Y, U, S,
K, etc... combinators, for example). The colloquial usage generally implies
something like a higher order function that does something interesting
(and possibly DSL-y).
Kris
On Sat, Aug 24, 2013 at 12:09 AM, damodar
Maybe an unlimited stack size should be the default?
As far as I understand, the only negative effect would be that some
programming mistakes would not result in a stack overflow. However, I
doubt the usefulness of that:
* It already depends a lot on the optimisation level
* If you do the same
On 13-08-26 04:46 AM, Niklas Hambüchen wrote:
Effectively, sequence is a partial function.
(Note: We are not trying to obtain a lazy list of random numbers, use
any kind of streaming or the likes. We want the list in memory and use it.)
We noticed that this problem did not happen if sequence
I'm sick for checking whether package is obsolete or not.
I think packages build failed long time ago should be collected and moved
to another page until someone fix them, or hackage pages should have a
filter for checking obsolete packages.
___
Tobias Dammers wrote:
IIRC you can use haskell-src-exts to parse a string into TH AST
structures. There might even be a quasi-quoter for that; I don't have a
real computer at hand right more, so you'll need to do some research of
your own.
Thanks Tobias, it led me to the right path. There is
On Sun, Aug 25, 2013 at 12:48 AM, He-chien Tsai depot...@gmail.com wrote:
I'm sick for checking whether package is obsolete or not.
I think packages build failed long time ago should be collected and moved
to another page until someone fix them, or hackage pages should have a
filter for
There's a
proposalhttp://ghc.haskell.org/trac/ghc/blog/Template%20Haskell%20Proposal#PartD:quasiquotationfor
adding a proper Haskell
QuasiQuoter as part of template-haskell. Until then, as others have noted
your best option is the haskell-src-meta package, but be aware that this
uses a separate
Austin: Do you have any update on this?
On 11/08/13 04:48, Austin Seipp wrote:
Henning,
Thanks for the report. I'm currently investigating this, and think it
should be possible to keep all of the old URLs intact.
On Sat, Aug 10, 2013 at 11:01 AM, Niklas Hambüchen m...@nh2.me wrote:
On
On Sat, Aug 24, 2013 at 11:00 AM, TP paratribulati...@free.fr wrote:
that has type Stmt, in an ExpQ that seems to be the only thing that we can
put in a splice. I have found that it can only be done by doE (or DoE) and
compE (or CompE) according to
Thanks. I found the explanation given at the link quite useful in shedding
the confusion I had had.
Thanks and regards,
-Damodar Kulkarni
On Sat, Aug 24, 2013 at 10:57 AM, Jason Dagit dag...@gmail.com wrote:
On Fri, Aug 23, 2013 at 9:09 PM, damodar kulkarni
kdamodar2...@gmail.comwrote:
Hi everybody,
I continue to learn and test Template Haskell (one more time thanks to John
Lato for his post at:
http://www.mail-archive.com/haskell-cafe@haskell.org/msg106696.html
that made me understand a lot of things).
I have a question about the way Template Haskell is working. Why
Hello,
Maybe you could have a look at Quasi
Quotationhttp://www.haskell.org/haskellwiki/Quasiquotation
.
Regards
J-C
On Sat, Aug 24, 2013 at 11:36 AM, TP paratribulati...@free.fr wrote:
Hi everybody,
I continue to learn and test Template Haskell (one more time thanks to John
Lato for his
IIRC you can use haskell-src-exts to parse a string into TH AST structures.
There might even be a quasi-quoter for that; I don't have a real computer
at hand right more, so you'll need to do some research of your own.
On Aug 24, 2013 11:37 AM, TP paratribulati...@free.fr wrote:
Hi everybody,
I
Excerpts from TP's message of Sat Aug 24 11:36:04 +0200 2013:
Haskell does not propose something similar to Python (or bash) exec() or
eval(), i.e. does not offer the possibility to take a (quoted) string in
You actually have eval/exec like features. You can run ghc modules in a
haskell
That's not a GHC flag; it's a haddock flag. Haddock (which, in case you're
not familiar with it, is a program to generate documentation from Haskell
source code) uses GHC, and the `optghc` flag lets you pass options to GHC
when you invoke Haddock. See [the Haddock docs of the 6.12 era][1], on page
Hello Cafe,
I was playing around with TypeLits in combination with Typeable (using
GHC 7.7.7.20130812 FWIW), but was surprised to find Symbols aren't
Typeable, and as such the following doesn't work. Is this intentional,
or am I missing something?
Thanks,
Nicolas
{-# LANGUAGE DataKinds,
Hi.
On 23 August 2013 13:29, Nicolas Trangez nico...@incubaid.com wrote:
Did anyone ever consider using type-level literals (strings) to 'name'
effects (or transformer layers when using monad stacks)?
Edwin Brady had this in his effects library in Idris.
Hi,
I continue to test Template Haskell, and I have some difficulties to use a
splice $() in a do contained in the main part of a program. Here is an
example. I want to make a splice that does `let a=a` in my code.
$ cat MakeLetStatement.hs
{-# LANGUAGE
On Sat, Aug 24, 2013 at 11:00 AM, TP paratribulati...@free.fr wrote:
main = do
$(makeLetStatement a)
-- print a
Is that the actual indentation you used? Because it's wrong if so, and the
error you would get is the one you're reporting. Indentation matters in
Haskell.
In an equation for
Brandon Allbery wrote:
main = do
$(makeLetStatement a)
-- print a
Is that the actual indentation you used? Because it's wrong if so, and the
error you would get is the one you're reporting. Indentation matters in
Haskell.
Yes, it matters, but not after main = do: all the lines can
Mateusz Kowalczyk fuuzetsu at fuuzetsu.co.uk writes:
I always thought [hayoo] was just Hoogle with more indexed docs.
Wait - there's a semantic difference:
hoogle does understand type signatures
(e.g., it can specialize them, or flip arguments of functions)
while hayoo just treats signatures
I must stress that OpenUnion1.hs described (briefly) in the paper
is only one implementation of open unions, out of many possible.
For example, I have two more implementations. A year-old version of
the code implemented open unions *WITHOUT* overlapping instances or
Typeable.
On Thu, Aug 22, 2013 at 9:23 PM, Mateusz Kowalczyk
fuuze...@fuuzetsu.co.uk wrote:
On 22/08/13 19:30, jabolo...@google.com wrote:
Hi,
I noticed Hayoo appears as a link in the toolbox of
http://hackage.haskell.org and also that Hayoo seems to display better
results than Hoogle. For example,
Hi all
Using the Conduit library is it possible to write the function:
eitherSrc :: MonadResource m
= Source m a - Source m b - Source m (Either a b)
which combines two sources into new output source such that data being
produced aysnchronously by the original two sources will
On Fri, Aug 23, 2013 at 10:12:27AM +0200, Erik Hesselink wrote:
Note that the 'normal' hoogle indexes all (?) of hackage. But by
default it only searches the haskell platform. You can add a package
with '+' to search in that package. E.g. PublicKey +crypto-api.
If the idea behind this, that
You can build this up using the = operator[1] in stm-conduit, something
like:
eitherSrc :: MonadResourceBase m
= Source (ResourceT m) a - Source (ResourceT m) b - Source
(ResourceT m) (Either a b)
eitherSrc src1 src2 = do
join $ lift $ Data.Conduit.mapOutput Left src1 =
Hi everybody,
There is something I do not understand in the way typeclass constraints are
inferred.
1/ Take the following function definition:
sum' [] = []
sum' (x:xs) = x + sum' xs
GHCI correctly gives:
:t sum'
sum' :: Num [a] = [[a]] - [a]
So it has inferred that the type list has to
Hi TP,
The difference is that in your second example, you have specified the
type signature
p :: a - ExpQ
so GHC checks whether p has this type, and correctly objects that it
doesn't. If you leave off the type signature, as you did for sum', the
right thing will be inferred.
Hope this helps,
On 23 August 2013 19:23, TP paratribulati...@free.fr wrote:
Hi everybody,
There is something I do not understand in the way typeclass constraints are
inferred.
1/ Take the following function definition:
sum' [] = []
sum' (x:xs) = x + sum' xs
You haven't specified a type signature here,
Adam Gundry wrote:
If you leave off the type signature, as you did for sum', the
right thing will be inferred.
Thanks Adam and Ivan. Very stupid question...
TP
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On Fri, 2013-08-23 at 08:06 +, o...@okmij.org wrote:
It will
arbitrarily pick the first match in the former and fail to compile
in
the latter case.
Of course we can have duplicate layers. In that case, the dynamically
closest
handler wins -- which sounds about right (think of reset
It's a bit pointless, if I have to know the package, where I want to
search in.
Yeah! It does sound a bit pointless. Hoogle should search everything
by default, and then you can refine your search by clicking on the '+'
or '-' on the packages that appear on the left menu.
Jose
--
Jose
On 23/08/13 14:57, jabolo...@google.com wrote:
It's a bit pointless, if I have to know the package, where I want to
search in.
Yeah! It does sound a bit pointless. Hoogle should search everything
by default, and then you can refine your search by clicking on the '+'
or '-' on the packages
Dear all,
our monthly Haskell Meeting will take place next week, Monday the 26th
of August, at 19h30 in Munich. Please note that we will meet this time
at the Max-Emanuel-Brauerei[1]. Last time, much more people showed up
than registered and our table was pretty cramped: thus, if you plan to
On 13-08-22 04:04 PM, Petr Pudlák wrote:
Or, if there are no such definitions, where would be a good place to add
them?
If they are to be added to the base libraries, the Data.Monoid module
would be my choice.
I did wish I had the AppMonoid instance on several occasions, when
using
Hi,
I am using GHC version 6.12.1.
What is optghc ?
I can't find that information anywhere...
Thanks,
Jose
--
Jose Antonio Lopes
Ganeti Engineering
Google Germany GmbH
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