Comment typos only

compiler/basicTypes/Demand.lhs

@@ -819,7 +819,7 @@ retCPR_maybe (RetSum t)  = Just t
 retCPR_maybe RetProd     = Just fIRST_TAG
 retCPR_maybe NoCPR       = Nothing
 
--- See Notes [Default demand on free variales]
+-- See Notes [Default demand on free variables]
 -- and [defaultDmd vs. resTypeArgDmd]
 defaultDmd :: Termination r -> JointDmd
 defaultDmd Diverges = botDmd
@@ -839,7 +839,7 @@ Note [defaultDmd and resTypeArgDmd]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 These functions are similar: They express the demand on something not
-explictitly mentioned in the environment resp. the argument list. Yet they are
+explicitly mentioned in the environment resp. the argument list. Yet they are
 different:
  * Variables not mentioned in the free variables environment are definitely
    unused, so we can use absDmd there.

compiler/simplCore/OccurAnal.lhs

@@ -200,7 +200,7 @@ These conditions apply regardless of the activation of the RULE (eg it might be
 inactive in this phase but become active later).  Once a Rec is broken up
 it can never be put back together, so we must be conservative.
 
-The principle is that, regardless of rule firings, every variale is
+The principle is that, regardless of rule firings, every variable is
 always in scope.
 
   * Note [Rules are extra RHSs]

compiler/typecheck/TcValidity.lhs

@@ -1009,7 +1009,7 @@ Here the instance decl really looks like
 but the k's are not scoped, and hence won't match Uniques.
 
 So instead we just match structure, with tcMatchTyX, and check
-that distinct type variales match 1-1 with distinct type variables.
+that distinct type variables match 1-1 with distinct type variables.
 
 HOWEVER, we *still* make the instance type variables scope over the
 type instances, to pick up non-obvious kinds.  Eg

docs/ndp/vect.tex

@@ -50,7 +50,7 @@ representing dictionaries of type-dependent operations on parallel arrays:
 \end{haskell}
 
 In vectorised code, polymorphic functions must be supplied with a \<PA\>
-dictionary for each type varialbe. For instance, \<\Lambda\alpha.e\> turns
+dictionary for each type variable. For instance, \<\Lambda\alpha.e\> turns
 into \<\Lambda\alpha.\lambda{dPA_\alpha}::PA \alpha.e'\>.
 
 For higher-kinded type variables, we expect a function of appropriate type