Edit README.md about OverloadedString pragma in .ghci

README.md

@@ -100,9 +100,9 @@ cabal build
 ```
 
 Loading IHaskell into GHCi for testing:
-If you want to play around with IHaskell by loading it into GHCi, you need to include the ghc package and the cabal macros file. cabal_macros.h is generated by the ```cabal build``` command and the file is placed in the build directory. So if you are at the top level of the IHaskell project, you can load GHCi as follows: 
+If you want to play around with IHaskell by loading it into GHCi, you need to include the ghc package and the cabal macros file. cabal_macros.h is generated by the ```cabal build``` command and the file is placed in the build directory. You will also need to use the OverloadedStrings language extension. So if you are at the top level of the IHaskell project, you can load GHCi as follows: 
 ```bash
-ghci -package ghc -optP-include -optPdist/build/autogen/cabal_macros.h
+ghci -XOverloadedStrings -package ghc -optP-include -optPdist/build/autogen/cabal_macros.h
 ```
 
 or you can create a .ghci file in the top level directory, like so: 
@@ -113,5 +113,6 @@ or you can create a .ghci file in the top level directory, like so:
 :set -package ghc
 :set -package ghc-paths
 :set -optP-include -optPdist/build/autogen/cabal_macros.h
+:set -XOverloadedStrings
 ```