add alternative simple graph constructor

modules/graph/src/main/scala/package.scala

@@ -7,7 +7,28 @@ import scalax.collection.immutable
 
 /** Graph-related operations */
 package object graph:
-  private[graph] type SimplestGraph[N] = immutable.Graph[N, UnDiEdge[N]]
+  type SimplestGraph[N] = immutable.Graph[N, UnDiEdge[N]]
+
+  /** Construct a simple graph from an adjancency list/'matrix'.
+    *
+    * @tparam N
+    *   The node type
+    * @param adj
+    *   The adjacency list / 'matrix' which encodes the edge relationships / node adjacencies
+    */
+  def buildSimpleGraph[N](adj: List[(N, Set[N])]): SimplestGraph[N] =
+    val singleGraphs = adj.map(fromSingleNodeAndNeighbors[N].tupled)
+    monoidKForSimplestGraphByOuterElements.combineAllK(singleGraphs)
+
+  /** Construct a simple graph from a set of nodes and set of edge endpoints.
+    *
+    * @tparam N
+    *   The node type
+    * @param adj
+    *   The endpoints of edges to build
+    */
+  def buildSimpleGraph[N](nodes: Set[N], endpoints: Set[(N, N)]): SimplestGraph[N] =
+    immutable.Graph.from(nodes, endpoints.map(_ ~ _))
 
   /** Start with an empty graph, and combine by taking union of node and edge sets. */
   def monoidKForSimplestGraphByOuterElements: MonoidK[SimplestGraph] = new:
@@ -20,15 +41,4 @@ package object graph:
 
   private def fromSingleNodeAndNeighbors[N](n: N, neighbors: Set[N]): SimplestGraph[N] =
     immutable.Graph.from(Set(n), neighbors.map(n ~ _))
-
-  /** Construct a simple graph from an adjancency list/'matrix'.
-    *
-    * @tparam N
-    *   The node type
-    * @param adj
-    *   The adjacency list / 'matrix' which encodes the edge relationships / node adjacencies
-    */
-  def buildSimpleGraph[N](adj: List[(N, Set[N])]): SimplestGraph[N] =
-    val singleGraphs = adj.map(fromSingleNodeAndNeighbors[N].tupled)
-    monoidKForSimplestGraphByOuterElements.combineAllK(singleGraphs)
 end graph