trying to use happstack, got it to install correctly on windows but now it's chucking out some errors when I compile my test class any input would be appreciated.
module Main where
import Happstack.Server
import Text.Blaze ((!))
import qualified Text.Blaze.Html4.Strict as H
import qualified Text.Blaze.Html4.Strict.Attributes as A
appTemplate :: String -> [H.Html] -> H.Html -> H.Html
appTemplate title headers body =
H.html $ do
H.head $ do
H.title (H.toHtml title)
H.meta ! A.httpEquiv "Content-Type"
! A.content "text/html;charset=utf-8"
sequence_ headers
H.body $ do
body
helloBlaze :: ServerPart Response
helloBlaze =
ok $ toResponse $
appTemplate "Hello, Blaze!"
[H.meta ! A.name "keywords"
! A.content "happstack, blaze, html"
]
(H.p $ do "Hello, "
H.b "blaze-html!")
main :: IO ()
main = simpleHTTP nullConf $ helloBlaze
I created a happstack folder and used cabal to install the required files to this folder, but when I compile the code I get the errors below.
Main.hs:13:30:
Couldn't match expected type ‘H.AttributeValue’
with actual type ‘[Char]’
In the first argument of ‘A.httpEquiv’, namely ‘"Content-Type"’
In the second argument of ‘(!)’, namely
‘A.httpEquiv "Content-Type"’
In the first argument of ‘(!)’, namely
‘H.meta ! A.httpEquiv "Content-Type"’
Main.hs:14:28:
Couldn't match expected type ‘H.AttributeValue’
with actual type ‘[Char]’
In the first argument of ‘A.content’, namely
‘"text/html;charset=utf-8"’
In the second argument of ‘(!)’, namely
‘A.content "text/html;charset=utf-8"’
In a stmt of a 'do' block:
H.meta ! A.httpEquiv "Content-Type"
! A.content "text/html;charset=utf-8"
Main.hs:23:34:
Couldn't match expected type ‘H.AttributeValue’
with actual type ‘[Char]’
In the first argument of ‘A.name’, namely ‘"keywords"’
In the second argument of ‘(!)’, namely ‘A.name "keywords"’
In the first argument of ‘(!)’, namely ‘H.meta ! A.name "keywords"’
Main.hs:24:37:
Couldn't match expected type ‘H.AttributeValue’
with actual type ‘[Char]’
In the first argument of ‘A.content’, namely
‘"happstack, blaze, html"’
In the second argument of ‘(!)’, namely
‘A.content "happstack, blaze, html"’
In the expression:
H.meta ! A.name "keywords" ! A.content "happstack, blaze, html"
Main.hs:26:27:
Couldn't match type ‘[]’ with ‘Text.Blaze.Internal.MarkupM’
Expected type: Text.Blaze.Internal.MarkupM Char
Actual type: [Char]
In a stmt of a 'do' block: "Hello, "
In the second argument of ‘($)’, namely
‘do { "Hello, ";
H.b "blaze-html!" }’
In the third argument of ‘appTemplate’, namely
‘(H.p
$ do { "Hello, ";
H.b "blaze-html!" })’
Main.hs:27:31:
Couldn't match type ‘[Char]’ with ‘Text.Blaze.Internal.MarkupM ()’
Expected type: H.Html
Actual type: [Char]
In the first argument of ‘H.b’, namely ‘"blaze-html!"’
In a stmt of a 'do' block: H.b "blaze-html!"
In the second argument of ‘($)’, namely
‘do { "Hello, ";
H.b "blaze-html!" }’
In the lines like this:
Couldn't match expected type ‘H.AttributeValue’
with actual type ‘[Char]’
compiler complains that it expected to receive H.AttributeValue but got [Char].
AttributeValue is defined here. As you can see, it is an instance of IsString, that means that you can make use of OverloadedStrings which is a language extension. To enable it put
{-# LANGUAGE OverloadedStrings #-}
at the top of your file.
This will rewrite fragments like this:
A.httpEquiv "Content-Type"
to something like this:
A.httpEquiv (fromString "Content-Type")
and fromString comes from IsString class which is defined here, as:
class IsString a where
fromString :: String -> a