On Nov 18, 2007 10:22 PM, Ryan Ingram [EMAIL PROTECTED] wrote:
[snip]
data Prompt (p :: * - *) :: (* - *) where
PromptDone :: result - Prompt p result
-- a is the type needed to continue the computation
Prompt :: p a - (a - Prompt p result) - Prompt p result
[snip]
runPromptM
Currently, yes; I was experimenting with type families. But it's pretty
simple to get it to compile on 6.6.1:
- remove the {-# LANGUAGE #-} pragma and replace with {-# OPTIONS_GHC
-fglasgow-exts -fallow-undecidable-instances #-}
- change the class declaration for MonadPrompter from
class Monad
I posted the current version of this code at
http://ryani.freeshell.org/haskell/
On 12/28/07, Thomas Hartman [EMAIL PROTECTED] wrote:
Would you mind posting the code for Prompt used by
import Prompt
I tried using Prompt.lhs from your first post but it appears to be
incompatible with the
Would you mind posting the code for Prompt used by
import Prompt
I tried using Prompt.lhs from your first post but it appears to be
incompatible with the guessing game program when I got tired of
reading the code and actually tried running it.
best, thomas.
2007/12/4, Ryan Ingram [EMAIL
Ask and ye shall receive. A simple guess-a-number game in MonadPrompt
follows.
But before I get to that, I have some comments:
Serializing the state at arbitrary places is hard; the Prompt contains a
continuation function so unless you have a way to serialize closures it
seems like you lose.
Thank you!
I really appreciate your explanation, and I hope this will enable me
to do some interesting and usefull stuff, in addition to firming up my
understanding of some of the more advanced haskell type system
features.
MACID is a sort of RDBMS replacement used as a backend by the HAppS
web
will be saved if I
understand correctly.
t.
Ryan Ingram [EMAIL PROTECTED]
Sent by: [EMAIL PROTECTED]
11/18/2007 07:22 PM
To
haskell haskell-cafe@haskell.org
cc
Subject
[Haskell-cafe] An interesting monad: Prompt
(This message is a literate haskell file. Code for the Prompt monad is
preceded
Also, I didn't realize this at first, but in order to use any of the
MonadTrans instances, like having StateT s (Prompt p) automatically be a
MonadPrompt, you sadly also need -fallow-overlapping-instances.
This is because MonadTrans monads looks a lot like Prompt.
arbitrary MonadTrans monad:
t
Looks very cool. So I tried playing with this code, unfortunately
couldn't get it to compile.
Could you double check that what you posted compiles, and if it does,
any idea what I'm doing wrong?
This is with
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
thanks, t.
Prelude :r
fwiw, if I comment those two lines around 141 out, it compiles.
t.
2007/11/24, Thomas Hartman [EMAIL PROTECTED]:
Looks very cool. So I tried playing with this code, unfortunately
couldn't get it to compile.
Could you double check that what you posted compiles, and if it does,
any idea what
-- Just for fun, make it work with StateT as well
-- (needs -fallow-undecidable-instances)
instance (Monad (t m), MonadTrans t, MonadPrompt p m) = MonadPrompt p
(tm) where
prompt = lift . prompt
Looks like that should be MonadPrompt p (t m) rather than (tm). Note the
space.
-Brent
that did it, thanks.
2007/11/24, Brent Yorgey [EMAIL PROTECTED]:
-- Just for fun, make it work with StateT as well
-- (needs -fallow-undecidable-instances)
instance (Monad (t m), MonadTrans t, MonadPrompt p m) = MonadPrompt p
(tm) where
prompt = lift . prompt
Looks like
(This message is a literate haskell file. Code for the Prompt monad is
preceded by ; code for my examples is preceded by ] and isn't complete,
but intended for illustration.)
I've been trying to implement a few rules-driven board/card games in Haskell
and I always run into the ugly problem of
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