Dear List,
I've been stumped for a few months on the following example, from
chapter 13 of LYH
http://learnyouahaskell.com/for-a-few-monads-more#useful-monadic-functions
runState (join (State $ \s -> (push 10,1:2:s))) [0,0,0]
I find the following implementation of join in the text is hard to
understand or apply
join :: (Monad m) => m (m a) -> m a
join mm = do
m <- mm
m
In contrast, I find the following definition(?) on Haskell Wikibooks
https://en.wikibooks.org/wiki/Haskell/Category_theory#Monads
join :: Monad m => m (m a) -> m a
join x = x >>= id
easier to understand, and although I can apply it to the following
Writer Monad example, in the same section of LYH,
runWriter $ join (Writer (Writer (1,"aaa"),"bbb"))
I cannot apply it to the State Monad example.
Regards,
- Olumide
Hello, I try to reproduce this kind of python code into haskell
--- python -- whcih use the suds module
cj = CookieJar()
url_opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
transport = HttpAuthenticated(username=self.getIspybUserName(),
password=self.getIspybPassWord())
service_name = "ToolsForCollectionWebService"
url = "http://195.221.10.20/ispyb-ws/ispybWS/ToolsForCollectionWebService?wsdl"
collectionWSClient = Client(url, transport=transport, timeout=3)
collect_params = collectionWSClient.service.findDataCollection(dataCollectionId)---
---
Has you can see, I create a Transport whcih need an Authentification and also I need to use a cookieJar in oder to manage the connection.
The a soap client is instanciated from the url and with this transport.
Then the findDatacollection service is called.
Now I would like to reproduce this with Haskell and the soap package (or not if it is easier without)
I started like this
getDataCollection :: Transport -> Int -> IO Response
getDataCollection t i = invokeWS t url () body parser
where
url = "http://195.221.10.20/ispyb-ws/ispybWS/ToolsForCollectionWebService?wsdl" -- ?wsdl/findDatacollection"
body = elementA "ToolsForCollectionWebService" [("xmlns", "findDataCollection")]
$ element "dataCollectionID" i
parser = StreamParser
. flaxTag ""
$ response
response = Response
<$> flaxContent "filePath"
main :: IO ()
main = do
-- Initial one-time preparations.
transport <- initTransportWithM defaultManagerSettings url pure pure
response <- getDataCollection transport dataCollectionID
print response
And When I run this I have this message
autoprocessing-exe: HttpExceptionRequest Request {
host = "xxx.xxx.xxx.xxx"
port = 80
secure = False
requestHeaders = [("Content-Type","text/xml; charset=utf-8"),("SOAPAction","http://195.221.10.20/ispyb-ws/ispybWS/ToolsForCollectionWebService?wsdl")]
path = "/ispyb-ws/ispybWS/ToolsForCollectionWebService"
queryString = ""
method = "POST"
proxy = Nothing
rawBody = False
redirectCount = 10
responseTimeout = ResponseTimeoutMicro 15000000
requestVersion = HTTP/1.1
}
TlsNotSupported
I know that I do not want the https, the url is http and not https.
now I do not know how to modify this in order to deal with the authentification and the cookiesJar.
It seems here that proxy is Nothing so I hope thqht it will use the http[s]_proxy environment variable.
thanks for your help.
Frederic
In the Haskell litrature desugaring of type clases to a data type is
mentioned.
For example:
class Foo a where
quux :: a -> Int
muux :: a -> Bool
Desugared to
data FooD a = FooD -- class Foo a where
{ quuxD :: a -> Int -- quux :: a -> Int
, muuxD :: a -> Bool -- muux :: a -> Bool
}
Is there any way using core dumps to actuall view the desugring of classes,
sub-classes, and instances, in my own code?
I have tried:
ghc -c -ddump-ds Foo.hs
But I cannot understand the output.
Thanks,
Pat
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