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Today's Topics:
1. Map instances in the list-tries package (Matthew Moppett)
2. Re: Map instances in the list-tries package (Stephen Tetley)
3. Re: Map instances in the list-tries package (Matthew Moppett)
4. Re: FFI export lazy list of string (Alexander.Vladislav.Popov )
5. llvm haskell bindings (Philippe Sismondi)
6. Re: llvm haskell bindings (Antoine Latter)
7. error logging (Dennis Raddle)
8. Re: error logging (Stephen Tetley)
----------------------------------------------------------------------
Message: 1
Date: Mon, 19 Dec 2011 23:02:42 +1100
From: Matthew Moppett <[email protected]>
Subject: [Haskell-beginners] Map instances in the list-tries package
To: [email protected]
Message-ID:
<CAMLEjZDz+yfk_n9ExNYxQ4urAtwe6nnJPJVENA=adw1nozc...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
I want to use the list-tries package for a little hobby project, but my
naive idea about how it should work is obviously wrong:
module TryPat where
import Data.ListTrie.Patricia.Map
a = singleton "harry" 99
yields the error:
No instance for (Data.ListTrie.Base.Map.Map map0 Char)
arising from a use of `singleton'
Possible fix:
add an instance declaration for
(Data.ListTrie.Base.Map.Map map0 Char)
In the expression: singleton "harry" 99
In an equation for `a': a = singleton "harry" 99
Now, there is some stuff about this in the docs:
The data types are parametrized over the map type they use internally to
store the child nodes: this allows extending them to support different
kinds
of key types or increasing efficiency. Child maps are required to be
instances of the Map class in
Data.ListTrie.Base.Map<http://hackage.haskell.org/packages/archive/list-tries/0.4.1/doc/html/Data-ListTrie-Patricia-Map.html>.
Some operations
additionally require an OrdMap instance.
But frankly, I don't understand it, especially the type signatures. Any
hints on how I might go about making an instance for Map map0 Char?
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Message: 2
Date: Mon, 19 Dec 2011 14:07:28 +0000
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] Map instances in the list-tries
package
To: Matthew Moppett <[email protected]>
Cc: [email protected]
Message-ID:
<CAB2TPRC0t0QMSXWt5=cfqng9rs3d+pvzz_+94sk5+0melc7...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi Matthew
You'll have to give `a` a concrete type, as `singleton` is overloaded,
GHC cannot infer a type.
The TrieMap type is quite complicated as it allows different
representations of (finite) Maps within it. There are three different
internal maps you can use (the three pre-defined instances of the Map
class - Data.Map, WrappedIntMap and AList) - I'd go for Data.Map as it
will be faster than AList and I think you are using Char for key so
you can't use an IntMap.
I don't have the package `list-tries` installed but I'd guess at one
of these two for the concrete type signature.
Assuming you have imported Data.Map as
import qualified Data.Map as Map
(Probably this...)
a :: TrieMap Map.Map [Char] Int
(Possibly this...)
a :: TrieMap (Map.Map Char Int) [Char] Int
------------------------------
Message: 3
Date: Tue, 20 Dec 2011 02:52:10 +1100
From: Matthew Moppett <[email protected]>
Subject: Re: [Haskell-beginners] Map instances in the list-tries
package
To: Stephen Tetley <[email protected]>
Cc: [email protected]
Message-ID:
<CAMLEjZBOvf1EbvUn7TWA54D64-fMw_zfnx_=f7ygsqqvzoe...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Thanks a lot, Stephen - was just about giving up on this.
The correct type signature turned out to be:
import Data.ListTrie.Patricia.Map as P
import qualified Data.Map as Map
a :: P.TrieMap Map.Map Char Int
a = P.singleton "harry" 99
On Tue, Dec 20, 2011 at 1:07 AM, Stephen Tetley <[email protected]>wrote:
> Hi Matthew
>
> You'll have to give `a` a concrete type, as `singleton` is overloaded,
> GHC cannot infer a type.
>
> The TrieMap type is quite complicated as it allows different
> representations of (finite) Maps within it. There are three different
> internal maps you can use (the three pre-defined instances of the Map
> class - Data.Map, WrappedIntMap and AList) - I'd go for Data.Map as it
> will be faster than AList and I think you are using Char for key so
> you can't use an IntMap.
>
> I don't have the package `list-tries` installed but I'd guess at one
> of these two for the concrete type signature.
>
> Assuming you have imported Data.Map as
>
> import qualified Data.Map as Map
>
> (Probably this...)
> a :: TrieMap Map.Map [Char] Int
>
>
> (Possibly this...)
> a :: TrieMap (Map.Map Char Int) [Char] Int
>
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Message: 4
Date: Mon, 19 Dec 2011 22:41:47 +0600
From: "Alexander.Vladislav.Popov "
<[email protected]>
Subject: Re: [Haskell-beginners] FFI export lazy list of string
To: "Edward Z. Yang" <[email protected]>
Cc: beginners <[email protected]>
Message-ID:
<calpbq9ahrbd6yuhhl-itv6tnys6ys9uujjlfqwc8z3drfyh...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi, Edward.
Thank you very much for your help. Very concisely.Russian say: brevity is
the sister of talent. I made my own naive
solution<http://rsdn.ru/forum/decl/4543044.1.aspx> which
based on VoidEx's advise <http://rsdn.ru/forum/decl/4541766.1.aspx>. In
Russian, but I think, you'll see the idea. It has some noise such as
CLazyList what is no more than code atavism from previous versions.
Happy hacking, too!
Alexander.
2011/12/16 Edward Z. Yang <[email protected]>
> I did a writeup for an even simpler example, which hopefully will give you
> the
> right idea how to do it in your case:
>
> http://blog.ezyang.com/2011/12/accessing-lazy-structures-from/
>
> Cheers,
> Edward
>
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Message: 5
Date: Mon, 19 Dec 2011 13:10:23 -0500
From: Philippe Sismondi <[email protected]>
Subject: [Haskell-beginners] llvm haskell bindings
To: Beginners Haskell <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
I am running OS X 10.6.8 with Xcode 4. I have the Haskell Platform installed,
ghc v. 7.0.3.
I cannot get the llvm haskell bindings to install correctly using cabal. I get
this at the tail end of messages from cabal:
checking llvm-c/Core.h usability... yes
checking llvm-c/Core.h presence... yes
checking for llvm-c/Core.h... yes
checking llvm/Support/DynamicLibrary.h usability... yes
checking llvm/Support/DynamicLibrary.h presence... yes
checking for llvm/Support/DynamicLibrary.h... yes
checking for LLVMModuleCreateWithName in -lLLVMCore... no
checking for LLVMModuleCreateWithName in -lLLVMCore... no
configure: error: could not find LLVM C bindings
cabal: Error: some packages failed to install:
llvm-0.10.0.1 failed during the configure step. The exception was:
ExitFailure 1
Has anyone had any luck getting this set up? Googling leads me to some rather
terse comments that the Apple llvm installation does not include the required
llvm libraries. I hate to install a separate set of llvm stuff with macports,
or the llvm repository, because I fear that I might run into all kinds of
puzzling conflicts with the Apple stuff.
Ideas?
- P -
------------------------------
Message: 6
Date: Mon, 19 Dec 2011 13:21:03 -0500
From: Antoine Latter <[email protected]>
Subject: Re: [Haskell-beginners] llvm haskell bindings
To: Philippe Sismondi <[email protected]>
Cc: Beginners Haskell <[email protected]>
Message-ID:
<CAKjSnQFNpyC99YrSjQunY=poo+pfgjgq7kmnuufjby7h1oh...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
On Mon, Dec 19, 2011 at 1:10 PM, Philippe Sismondi <[email protected]> wrote:
> I am running OS X 10.6.8 with Xcode 4. I have the Haskell Platform installed,
> ghc v. 7.0.3.
>
> I cannot get the llvm haskell bindings to install correctly using cabal. I
> get this at the tail end of messages from cabal:
>
> checking llvm-c/Core.h usability... yes
> checking llvm-c/Core.h presence... yes
> checking for llvm-c/Core.h... yes
> checking llvm/Support/DynamicLibrary.h usability... yes
> checking llvm/Support/DynamicLibrary.h presence... yes
> checking for llvm/Support/DynamicLibrary.h... yes
> checking for LLVMModuleCreateWithName in -lLLVMCore... no
> checking for LLVMModuleCreateWithName in -lLLVMCore... no
Here, configure has found LLVM C library, but the found library does
not have the functionality required.
> configure: error: could not find LLVM C bindings
So here configure reports that it cannot find LLVM C library.
> cabal: Error: some packages failed to install:
> llvm-0.10.0.1 failed during the configure step. The exception was:
> ExitFailure 1
>
>
> Has anyone had any luck getting this set up? Googling leads me to some rather
> terse comments that the Apple llvm installation does not include the required
> llvm libraries. I hate to install a separate set of llvm stuff with macports,
> or the llvm repository, because I fear that I might run into all kinds of
> puzzling conflicts with the Apple stuff.
>
It looks like your guess is correct - the LLVM C library you have
installed isn't what the Haskell bindings want.
> Ideas?
>
This might be where someone else jumps in - I've had luck with
MacPorts + Haskell in the past, but it can be a struggle. I've never
tried this particular case.
In particular the iconv situation is nightmarish (Apple iconv and
MacPorts iconv are not ABI compatible), but that's really a special
case of the more general problem of building things against MacPorts.
Antoine
------------------------------
Message: 7
Date: Mon, 19 Dec 2011 16:32:42 -0800
From: Dennis Raddle <[email protected]>
Subject: [Haskell-beginners] error logging
To: Haskell Beginners <[email protected]>
Message-ID:
<CAKxLvooCwrdhbT+EL6obL5PmaGSzjqSg4qXr4=fajohe7be...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Okay, I want to write code in the Either monad in order to throw errors
with logging. I did this a while ago but can't find my code and I forget
what I did.
Note that I'm using ghc 6.12.3, which I installed via the haskell platform.
First question is: do I use Control.Monad.Error or Control.Monad.Either?
Second question is: I want to have each monadic function within the stack
of functions that is currently running catch the error and add some context
to the log.
For instance I need to have a function called, let's say,
"catchAndAnnotate" that functions like the following. I'm just making this
up-- how is it really done?
func1 :: SomeType -> Either String SomeType
func1 x = ("running in func1 with argument " ++ show x) `catchAndAnnotate`
(do y <- somework x
when (isBad y) (throwError "oops")
return y)
somework :: SomeType -> Either String SomeType
somework x = ("running in somework with argument ++ show x)
`catchAndAnnotate` (whatever x)
whatever :: SomeType -> Either String SomeType
whatever = ...
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Message: 8
Date: Tue, 20 Dec 2011 07:55:36 +0000
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] error logging
To: Dennis Raddle <[email protected]>
Cc: Haskell Beginners <[email protected]>
Message-ID:
<cab2tprbcxydrgfxlj9reojmhff+m64qzfkfcg8xrdqmjexb...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi Dennis
If you want logging you probably want a Writer monad. Either / error
monads only support single message on failure. For logging you have to
pass an accumulator throughout the computation so it can store
messages - this is what Writer does.
If you want logging and error you probably want a combined Error and
Writer monad.
------------------------------
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