Merge pull request #2575 from ucsd-progsys/define-Integer-IS

Add assumption and define for GHC.Num.Integer.IS

Author: nikivazou

src/GHC/Num/Integer_LHAssumptions.hs

@@ -10,5 +10,7 @@ import GHC.Types_LHAssumptions()
 {-@
 assume GHC.Num.Integer.IS :: x:Int# -> {v: Integer | v = (x :: int) }
 
+define GHC.Num.Integer.IS x = (x)
+
 embed Integer as int
 @-}