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haskelldo-notation

In what does this simple do notation desugar to?

I'm using Aeson and Network.HTTP. I was able to encode a json and print it on the screen doing the following:

getCode :: String -> IO ResponseCode
getCode url = simpleHTTP req >>= getResponseCode
    where req = getRequest url

main :: IO ()
main = do 
    x <- get "http://jsonplaceholder.typicode.com/todos/1"
    let y = encode x
    B.putStrLn y

However I do not understand what this do expression desugars to. Something like this:

get "http://jsonplaceholder.typicode.com/todos/1" >>= (?)

what should be in the ??

I only know how to desugar this:

do { x1 <- action1
   ; x2 <- action2
   ; mk_action3 x1 x2 }

to this

action1 >>= (\ x1 -> action2 >>= (\ x2 -> mk_action3 x1 x2 ))

bu the way, what is an action? https://en.m.wikibooks.org/wiki/Haskell/do_notation does not explain very precisely.

Solution

  • get "http://jsonplaceholder.typicode.com/todos/1" >>= (\x -> let y = encode x in B.putStrLn y)