Directly re-export matrix-graph? as the opaque type Matrix-Graph.

graph.rkt

@@ -31,7 +31,7 @@
            unweighted-graph/directed unweighted-graph/adj
            weighted-graph? weighted-graph/undirected weighted-graph/directed
            undirected-graph directed-graph
-           matrix-graph?
+           (rename-out [g:matrix-graph? matrix-graph?])
 
            bfs bfs/generalized fewest-vertices-path
            dfs dfs/generalized
@@ -120,8 +120,6 @@
     (graph (g:directed-graph es ws)))
 
   ;; 2.3 Matrix Graphs
-  (define (matrix-graph? g)
-    (g:matrix-graph? (gg g)))
 
   ;; 4 Basic Graph Functions
   ;; 4.1 Breadth-first Search
@@ -245,6 +243,7 @@
 
 (require/typed/provide 'graph-wrapper
   [#:opaque Graph graph?]
+  [#:opaque Matrix-Graph matrix-graph?]
 
   ;; 1 Generic Graph Interface
   [has-vertex? (-> Graph Any Boolean)]
@@ -283,7 +282,6 @@
   [directed-graph (->* ((Listof (List Any Any))) ((Listof Any)) Graph)]
 
   ;; 2.3 Matrix Graphs
-  [matrix-graph? (-> Graph Boolean)]
 
   ;; 4 Basic Graph Functions
   ;; 4.1 Breadth-first Search