Warn about unsupported operations in DummyCategory and support "list_of_lists_of_morphisms" in CategoryConstructor

CAP/PackageInfo.g

@@ -10,7 +10,7 @@ SetPackageInfo( rec(
 
 PackageName := "CAP",
 Subtitle := "Categories, Algorithms, Programming",
-Version := "2023.08-08",
+Version := "2023.08-09",
 Date := (function ( ) if IsBound( GAPInfo.SystemEnvironment.GAP_PKG_RELEASE_DATE ) then return GAPInfo.SystemEnvironment.GAP_PKG_RELEASE_DATE; else return Concatenation( ~.Version{[ 1 .. 4 ]}, "-", ~.Version{[ 6, 7 ]}, "-01" ); fi; end)( ),
 License := "GPL-2.0-or-later",
 

CAP/gap/CategoryConstructor.gi

@@ -288,7 +288,7 @@ InstallMethod( CategoryConstructor,
         info := CAP_INTERNAL_METHOD_NAME_RECORD.(name);
 
         # check if filters and return_type are known
-        unknown_filters := Filtered( info.filter_list, filter -> not filter in [ "category", "object", "morphism", "integer", "element_of_commutative_ring_of_linear_structure", "nonneg_integer_or_infinity", "list_of_objects", "list_of_morphisms", "pair_of_morphisms", "list_of_integers_and_list_of_morphisms" ] );
+        unknown_filters := Filtered( info.filter_list, filter -> not filter in [ "category", "object", "morphism", "integer", "element_of_commutative_ring_of_linear_structure", "nonneg_integer_or_infinity", "list_of_objects", "list_of_morphisms", "list_of_lists_of_morphisms", "pair_of_morphisms", "list_of_integers_and_list_of_morphisms" ] );
 
         if not IsEmpty( unknown_filters ) then
 
@@ -383,6 +383,10 @@ InstallMethod( CategoryConstructor,
 
                     return Concatenation( "List( ", argument_name, ", x -> ", options.underlying_morphism_getter_string, "( cat, x ) )" );
 
+                elif filter = "list_of_lists_of_morphisms" then
+
+                    return Concatenation( "List( ", argument_name, ", x -> List( x, y -> ", options.underlying_morphism_getter_string, "( cat, y ) ) )" );
+
                 elif filter = "pair_of_morphisms" then
 
                     return Concatenation( "Pair( ", options.underlying_morphism_getter_string, "( cat, ", argument_name, "[1] ), ", options.underlying_morphism_getter_string, "( cat, ", argument_name, "[2] ) )" );

CAP/gap/DummyCategory.gi

@@ -10,7 +10,7 @@
         [ IsRecord ],
 
   function( options )
-    local category_constructor_options, dummy_function, C;
+    local category_constructor_options, dummy_function, C, operation_name;
 
     category_constructor_options := ShallowCopy( options );
     category_constructor_options.category_filter := IsDummyCategory;
@@ -77,6 +77,16 @@
 
     Finalize( C );
 
+    for operation_name in options.list_of_operations_to_install do
+
+        if not CanCompute( C, operation_name ) then
+
+            Print( "WARNING: The dummy category cannot compute ", operation_name, ", probably because the operation is not supported by CategoryConstructor yet.\n" );
+
+        fi;
+
+    od;
+
     return C;
 
 end );