Re: [Haskell-cafe] cgi liftM liftIO

2008-06-14 Thread Adrian Neumann 
I think you need to put liftIO in front of the IO actions you want to  
do inside the CGI Monad. Like in this example


 http://www.haskell.org/haskellwiki/ 
Practical_web_programming_in_Haskell#File_uploads


(Why did I need to use google to find that? The wiki search in awful.  
Searching for CGI returns nothing, whereas with google the above is  
the first hit.)


Am 13.06.2008 um 15:41 schrieb Cetin Sert:


Hi,

Could someone please care to explain what I am doing wrong below in  
cgiMain2 and how can I fix it?



./Main.hs:25:15:
No instance for (MonadCGI IO)
  arising from a use of `output' at ./Main.hs:25:15-20
Possible fix: add an instance declaration for (MonadCGI IO)
In the first argument of `($)', namely `output'
In the expression: output $ renderHtml $ page import fileForm
In the definition of `upload':
upload = output $ renderHtml $ page import fileForm

./Main.hs:57:29:
Couldn't match expected type `CGI CGIResult'
   against inferred type `IO CGIResult'
In the first argument of `handleErrors', namely `cgiMain2'
In the second argument of `($)', namely `handleErrors cgiMain2'
In the expression: runCGI $ handleErrors cgiMain2


import IO
import Network.CGI
import Text.XHtml

import qualified Data.ByteString.Lazy as BS

import Control.Monad (liftM)
import Data.Maybe (fromJust)

import Interact

fileForm = form ! [method post, enctype multipart/form-data] 
 [afile file, submit  Upload]

page t b = header  thetitle  t +++ body  b

cgiMain1 = do
  getInputFPS file ↠ λms → maybe upload contents ms ↠ return
  where
upload   = output $ renderHtml $ page import fileForm
contents = outputFPS

cgiMain2 = do
  getInputFPS file ↠ λms → maybe upload contents ms ↠ return
  where
upload   = output $ renderHtml $ page import fileForm
contents = λs → do
  (i,o,h,_) ← runUnzip
  BS.hPutStr i s
  c ← BS.hGetContents o
  outputFPS c


{-
  (i,o,h,_) ← runUnzip
  BS.hPutStr i s
  BS.hGetContents o ↠ outputFPS
-}



{-
liftM :: (Monad m) = (a1 - r) - m a1 - m r
liftIO :: (MonadIO m) = IO a - m a

saveFile n =
do cont - liftM fromJust $ getInputFPS file
   let f = uploadDir ++ / ++ basename n
   liftIO $ BS.writeFile f cont
   return $ paragraph  (Saved as  +++ anchor ! [href f]   
f +++ .)

-}

runUnzip = runInteractiveCommand unzip -l /dev/stdin

main = runCGI $ handleErrors cgiMain2

Best Regards,
Cetin Sert

P/s: what are lifts o_O?
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Re: [Haskell-cafe] cgi liftM liftIO

2008-06-14 Thread Gwern Branwen 
On 2008.06.14 08:05:48 +0200, Adrian Neumann [EMAIL PROTECTED] scribbled 4.0K 
characters:
 I think you need to put liftIO in front of the IO actions you want to do
 inside the CGI Monad. Like in this example

  http://www.haskell.org/haskellwiki/
 Practical_web_programming_in_Haskell#File_uploads

 (Why did I need to use google to find that? The wiki search in awful.
 Searching for CGI returns nothing, whereas with google the above is the
 first hit.)

IIRC, MediaWiki search will not search for anything shorter than 4 characters 
(as an optimization, I think). This is admittedly annoying when you are 
searching not for 'the' but 'IRC' or 'CGI'...

--
gwern
William Gap subversives Lexis-Nexis SADMS Blowpipe GRU Posse ISCS mailbomb


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[Haskell-cafe] cgi liftM liftIO

2008-06-13 Thread Cetin Sert 
Hi,

Could someone please care to explain what I am doing wrong below in cgiMain2
and how can I fix it?


./Main.hs:25:15:
No instance for (MonadCGI IO)
  arising from a use of `output' at ./Main.hs:25:15-20
Possible fix: add an instance declaration for (MonadCGI IO)
In the first argument of `($)', namely `output'
In the expression: output $ renderHtml $ page import fileForm
In the definition of `upload':
upload = output $ renderHtml $ page import fileForm

./Main.hs:57:29:
Couldn't match expected type `CGI CGIResult'
   against inferred type `IO CGIResult'
In the first argument of `handleErrors', namely `cgiMain2'
In the second argument of `($)', namely `handleErrors cgiMain2'
In the expression: runCGI $ handleErrors cgiMain2


import IO
import Network.CGI
import Text.XHtml

import qualified Data.ByteString.Lazy as BS

import Control.Monad (liftM)
import Data.Maybe (fromJust)

import Interact

fileForm = form ! [method post, enctype multipart/form-data] 
 [afile file, submit  Upload]

page t b = header  thetitle  t +++ body  b

cgiMain1 = do
  getInputFPS file ↠ λms → maybe upload contents ms ↠ return
  where
upload   = output $ renderHtml $ page import fileForm
contents = outputFPS

cgiMain2 = do
  getInputFPS file ↠ λms → maybe upload contents ms ↠ return
  where
upload   = output $ renderHtml $ page import fileForm
contents = λs → do
  (i,o,h,_) ← runUnzip
  BS.hPutStr i s
  c ← BS.hGetContents o
  outputFPS c


{-
  (i,o,h,_) ← runUnzip
  BS.hPutStr i s
  BS.hGetContents o ↠ outputFPS
-}



{-
liftM :: (Monad m) = (a1 - r) - m a1 - m r
liftIO :: (MonadIO m) = IO a - m a

saveFile n =
do cont - liftM fromJust $ getInputFPS file
   let f = uploadDir ++ / ++ basename n
   liftIO $ BS.writeFile f cont
   return $ paragraph  (Saved as  +++ anchor ! [href f]  f +++
.)
-}

runUnzip = runInteractiveCommand unzip -l /dev/stdin

main = runCGI $ handleErrors cgiMain2

Best Regards,
Cetin Sert

P/s: what are lifts o_O?
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