I'm a beginner --- struggling with the SimpleJSON example from Real World Haskell
I'm sure this question has been asked many times but I have not been able to find it anywhere. I have written the code below into Lekseh directly from the RWH book. However, I always get the error parse error on input 'getString' and the line number refers to the type declaration for getString. I have no idea what's wrong and would appreciate any suggestions to get past this. Thanks in advance David ---------------------------- module SimpleJSON ( JValue(..), getString, getInt, getDouble, getBool, getObject, getArray, isNull ) where data JValue = JString String | JNumber Double | JBool Bool | JNull | JObject [ (String, JValue) ] | JArray [JValue] deriving (Eq, Ord, Show) getString :: JValue -> Maybe String getString (JString s) = Just s getString _ = Nothing getInt (JNumber n) = Just (truncate n) getInt _ = Nothing getDouble (JNumber n) = Just n getDouble _ = Nothing getBool (JBool b) = Just b getBool _ = Nothing getObject (JObject o) = Just o getObject _ = Nothing getArray (JArray a) = Just a getArray _ = Nothing isNull v = v == JNull -- View this message in context: http://haskell.1045720.n5.nabble.com/I-m-a-beginner-struggling-with-the-Simp... Sent from the Haskell - Haskell mailing list archive at Nabble.com.
Hi, Make sure the line data JValue ... is not indented. I should start at the first column. Patrick On Tue, Dec 14, 2010 at 4:28 PM, dhjdhj <dhjdhj@gmail.com> wrote:
I'm sure this question has been asked many times but I have not been able to find it anywhere.
I have written the code below into Lekseh directly from the RWH book. However, I always get the error
parse error on input 'getString' and the line number refers to the type declaration for getString.
I have no idea what's wrong and would appreciate any suggestions to get past this.
Thanks in advance
David ----------------------------
module SimpleJSON (
JValue(..), getString, getInt, getDouble, getBool, getObject, getArray, isNull )
where
data JValue = JString String | JNumber Double | JBool Bool | JNull | JObject [ (String, JValue) ] | JArray [JValue]
deriving (Eq, Ord, Show)
getString :: JValue -> Maybe String getString (JString s) = Just s getString _ = Nothing
getInt (JNumber n) = Just (truncate n) getInt _ = Nothing
getDouble (JNumber n) = Just n getDouble _ = Nothing
getBool (JBool b) = Just b getBool _ = Nothing
getObject (JObject o) = Just o getObject _ = Nothing
getArray (JArray a) = Just a getArray _ = Nothing
isNull v = v == JNull
-- View this message in context: http://haskell.1045720.n5.nabble.com/I-m-a-beginner-struggling-with-the-Simp... Sent from the Haskell - Haskell mailing list archive at Nabble.com.
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-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada
OMG --- that was it --- I can't tell you how many hours I have been wrestling with this. Thank you so much for the quick response. I was aware that Haskell required indentation for some things (and I'm a fan of indentation) but I didn't realize it required NO indentation for some things --- I thought that went away with FORTRAN (grin) D On Dec 14, 2010, at 4:37 PM, Patrick LeBoutillier wrote:
Hi,
Make sure the line
data JValue ...
is not indented. I should start at the first column.
Patrick
On Tue, Dec 14, 2010 at 4:28 PM, dhjdhj <dhjdhj@gmail.com> wrote:
I'm sure this question has been asked many times but I have not been able to find it anywhere.
I have written the code below into Lekseh directly from the RWH book. However, I always get the error
parse error on input 'getString' and the line number refers to the type declaration for getString.
I have no idea what's wrong and would appreciate any suggestions to get past this.
Thanks in advance
David ----------------------------
module SimpleJSON (
JValue(..), getString, getInt, getDouble, getBool, getObject, getArray, isNull )
where
data JValue = JString String | JNumber Double | JBool Bool | JNull | JObject [ (String, JValue) ] | JArray [JValue]
deriving (Eq, Ord, Show)
getString :: JValue -> Maybe String getString (JString s) = Just s getString _ = Nothing
getInt (JNumber n) = Just (truncate n) getInt _ = Nothing
getDouble (JNumber n) = Just n getDouble _ = Nothing
getBool (JBool b) = Just b getBool _ = Nothing
getObject (JObject o) = Just o getObject _ = Nothing
getArray (JArray a) = Just a getArray _ = Nothing
isNull v = v == JNull
-- View this message in context: http://haskell.1045720.n5.nabble.com/I-m-a-beginner-struggling-with-the-Simp... Sent from the Haskell - Haskell mailing list archive at Nabble.com.
_______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada
On Tuesday 14 December 2010 22:44:23, David Jameson wrote:
OMG --- that was it --- I can't tell you how many hours I have been wrestling with this.
Thank you so much for the quick response.
I was aware that Haskell required indentation for some things (and I'm a fan of indentation) but I didn't realize it required NO indentation for some things --- I thought that went away with FORTRAN (grin)
Well, you could have indented the rest of the code to the same level as the `data JValue'. The point is that all declarations at the same level must have the same indentation (unless you use explicit braces and semicolons).
D
participants (4)
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Daniel Fischer -
David Jameson -
dhjdhj
-
Patrick LeBoutillier