[eta-tour]: Missing info RecordWildCards

[nomisRev]

Source Code:

data Pair = Pair { pairX :: Int
                 , pairY :: Int }

myPair :: Pair
myPair = Pair { pairX = 1
              , pairY = 2 }

pairToString :: Pair -> String
pairToString Pair { pairX = x, pairY = y } =
  "("    show x   
  ","    show y    ")" 

main :: IO ()
main = putStrLn $ "myPair = "    pairToString myPair

Output:

Illegal `..' in record 
Use RecordWildCards to permit this

Dear Eta team,

First of all, I want to thank you for the awesome documentation! 👏 And on the amazing work, you guys are doing.

I am brand new to Eta or Haskell and couldn't compile the snippet locally because it was missing {-# LANGUAGE RecordWildCards #-}. I had no idea yet how to enable special compiler features and thought it would'be useful to add it to the page.

Cheers!

EDIT: Same with

• {-# LANGUAGE InstanceSigs #-} on page 46 (Typeclasses 7/7)
• {-# LANGUAGE RankNTypes #-} page 42 (Shapeshifting functions 3/7)

[Jyothsnasrinivas]

@nomisRev Thanks! We are actually going to enable many of those features by default in Eta v1.0. In the next iteration of the tour/docs we'll mention how to deal with Language Pragmas.

[nomisRev]

@Jyothsnasrinivas Thanks for the response :) Very happy to hear many of these features will be enabled by default!