[ derive ] Log used order using argument names too

src/Deriving/DepTyCheck/Gen/Core/ConsDerive.idr

@@ -238,7 +238,7 @@ namespace NonObligatoryExts
 
       let theOrder = searchOrder $ removeDeeply givs determ
 
-      logPoint {level=10} "least-effort.order" [sig, con] "- used final order: \{show theOrder}"
+      logPoint {level=10} "least-effort.order" [sig, con] "- used final order: \{interpolate @{WithNames} theOrder}"
 
       labelGen "\{show con.name} (orders)".label <$> genForOrder theOrder
 

src/Deriving/DepTyCheck/Util/Reflection.idr

@@ -56,6 +56,16 @@ SingleLogPosition Con where
     let fullName' = unpack fullName
     maybe fullName (pack . flip drop fullName' . S . finToNat) $ findLastIndex (== '.') fullName'
 
+export
+[WithName] {con : Con} -> Interpolation (Fin con.args.length) where
+  interpolate i = case name $ index' con.args i of
+    Nothing => "#\{show i}"
+    Just n  => "\{show n} (#\{show i})"
+
+export
+[WithNames] {con : Con} -> Foldable f => Interpolation (f $ Fin con.args.length) where
+  interpolate xs = joinBy ", " $ toList xs <&> interpolate @{WithName}
+
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 --- Compiler-based `TTImp` transformations ---
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