I wrote down some stuff from my first look at json, maybe it can help you in getting further? http://therning.org/magnus/archives/719 /M On Sun, May 15, 2011 at 09:51:28PM +0200, Adrien Haxaire wrote:
Hello,
I have this JSON string that I have put in a text file, test.json:
{"coordinates": [0.0, 1.0]}
using GHCi, I can read it like this:
s <- readFile "test.json" let r = decode s :: Result JSValue r Ok (JSObject (JSONObject {fromJSObject = [("coordinates",JSArray [JSRational False (0 % 1),JSRational False (1 % 1)])]}))
I want to affect this array of two Double to the type Coordinates being defined like this:
type Coordinates = (Double, Double)
Using this type I can create a Node:
data Node = Node Coordinates Number deriving (Eq, Ord, Show)
The problem is that I have no idea what to do with decoded JSValue. It seems I have to define an instance of JSON to read it. Does this mean using pattern matching to extract the values ?
What do I do with the Result type ? Should I get rid of it like this:
fromResult :: Result JSValue -> JSValue fromResult (Ok js) = js fromResult _ = JSNull
and work with the raw JValue ?
These questions might be trivial, but I know only imperative languages, which is why I like so much to learn Haskell and functional programming, lots to learn and discover :)
Many thanks in advance, Adrien
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