Typos in comments

compiler/simplCore/Simplify.hs

@@ -2644,7 +2644,7 @@ Note [Funky mkPiTypes]
 ~~~~~~~~~~~~~~~~~~~~~~
 Notice the funky mkPiTypes.  If the contructor has existentials
 it's possible that the join point will be abstracted over
-type varaibles as well as term variables.
+type variables as well as term variables.
  Example:  Suppose we have
         data T = forall t.  C [t]
  Then faced with

compiler/typecheck/TcHsType.hs

@@ -1374,7 +1374,7 @@ Here the type of x's first component is called 'a1' in one branch and
 they definitely won't have the sane lexical Name.
 
 I think we could solve this by recording in a SigTv a list of all the
-in-scope varaibles that it should not unify with, but it's fiddly.
+in-scope variables that it should not unify with, but it's fiddly.
 
 
 ************************************************************************

compiler/typecheck/TcSimplify.hs

@@ -634,7 +634,7 @@ and if so refrain from quantifying over *any* equalites.
 simplifyRule :: RuleName
              -> WantedConstraints       -- Constraints from LHS
              -> WantedConstraints       -- Constraints from RHS
-             -> TcM ([EvVar], WantedConstraints)   -- LHS evidence varaibles
+             -> TcM ([EvVar], WantedConstraints)   -- LHS evidence variables
 -- See Note [Simplifying RULE constraints] in TcRule
 simplifyRule name lhs_wanted rhs_wanted
   = do {         -- We allow ourselves to unify environment

compiler/typecheck/TcTyClsDecls.hs

@@ -1095,7 +1095,7 @@ Then in the family instance we want to
                      KindFam (Maybe k) k' a b = T k k' a b -> Int
 
 Notice that in the third step we quantify over all the visibly-mentioned
-type variables (a,b), but also over the implicitly mentioned kind varaibles
+type variables (a,b), but also over the implicitly mentioned kind variables
 (k, k').  In this case one is bound explicitly but often there will be
 none. The role of the kind signature (a :: Maybe k) is to add a constraint
 that 'a' must have that kind, and to bring 'k' into scope.