Merge pull request #667 from zickgraf/freyd_empty_limits

Support empty limits in FreydCategory

Author: sebastianpos

FreydCategoriesForCAP/PackageInfo.g

@@ -17,7 +17,7 @@ Version := Maximum( [
   ## this line prevents merge conflicts
   "2020.05-17", ## Mohamed's version
   ## this line prevents merge conflicts
-  "2021.05-02", ## Fabian's version
+  "2021.05-03", ## Fabian's version
   ## this line prevents merge conflicts
   "2020.04-18", ## Kamal's version
 ] ),

FreydCategoriesForCAP/gap/FreydCategory.gi

@@ -33,6 +33,12 @@ InstallGlobalFunction( FREYD_CATEGORY,
 
     freyd_category!.category_as_first_argument := true;
 
+    if IsBound( underlying_category!.supports_empty_limits ) then
+        
+        freyd_category!.supports_empty_limits := underlying_category!.supports_empty_limits;
+        
+    fi;
+    
     freyd_category!.compiler_hints := rec(
         category_attribute_names := [
             "UnderlyingCategory",
@@ -597,9 +603,10 @@ InstallGlobalFunction( INSTALL_FUNCTIONS_FOR_FREYD_CATEGORY,
     AddUniversalMorphismIntoDirectSumWithGivenDirectSum( category,
       function( cat, diagram, test_object, source, direct_sum_object )
 
-        return FreydCategoryMorphism( Source( source[1] ),
+        return FreydCategoryMorphism( test_object,
                                       UniversalMorphismIntoDirectSum( underlying_category,
                                                                       List( diagram, obj -> Range( RelationMorphism( obj ) ) ),
+                                                                      Range( RelationMorphism( test_object ) ),
                                                                       List( source, mor -> MorphismDatum( mor ) ) ),
                                       direct_sum_object
                                     );
@@ -624,8 +631,9 @@ InstallGlobalFunction( INSTALL_FUNCTIONS_FOR_FREYD_CATEGORY,
         return FreydCategoryMorphism( direct_sum_object,
                                       UniversalMorphismFromDirectSum( underlying_category,
                                                                       List( diagram, obj -> Range( RelationMorphism( obj ) ) ),
+                                                                      Range( RelationMorphism( test_object ) ),
                                                                       List( sink, mor -> MorphismDatum( mor ) ) ),
-                                      Range( sink[1] )
+                                      test_object
                                     );
 
     end );