+import Ratio ( numerator, denominator )
+import Outputable
+\end{code}
+
+%************************************************************************
+%* *
+ Desugaring literals
+ [used to be in DsExpr, but DsMeta needs it,
+ and it's nice to avoid a loop]
+%* *
+%************************************************************************
+
+We give int/float literals type @Integer@ and @Rational@, respectively.
+The typechecker will (presumably) have put \tr{from{Integer,Rational}s}
+around them.
+
+ToDo: put in range checks for when converting ``@i@''
+(or should that be in the typechecker?)
+
+For numeric literals, we try to detect there use at a standard type
+(@Int@, @Float@, etc.) are directly put in the right constructor.
+[NB: down with the @App@ conversion.]
+
+See also below where we look for @DictApps@ for \tr{plusInt}, etc.
+
+\begin{code}
+dsLit :: HsLit -> DsM CoreExpr
+dsLit (HsChar c) = returnDs (mkCharExpr c)
+dsLit (HsCharPrim c) = returnDs (mkLit (MachChar c))
+dsLit (HsString str) = mkStringLitFS str
+dsLit (HsStringPrim s) = returnDs (mkLit (MachStr s))
+dsLit (HsInteger i _) = mkIntegerExpr i
+dsLit (HsInt i) = returnDs (mkIntExpr i)
+dsLit (HsIntPrim i) = returnDs (mkIntLit i)
+dsLit (HsFloatPrim f) = returnDs (mkLit (MachFloat f))
+dsLit (HsDoublePrim d) = returnDs (mkLit (MachDouble d))
+
+dsLit (HsRat r ty)
+ = mkIntegerExpr (numerator r) `thenDs` \ num ->
+ mkIntegerExpr (denominator r) `thenDs` \ denom ->
+ returnDs (mkConApp ratio_data_con [Type integer_ty, num, denom])
+ where
+ (ratio_data_con, integer_ty)
+ = case tcSplitTyConApp ty of
+ (tycon, [i_ty]) -> ASSERT(isIntegerTy i_ty && tycon `hasKey` ratioTyConKey)
+ (head (tyConDataCons tycon), i_ty)