Hashtable was simply hiding; reinstate throughout

Dapper.StrongName/project.json

@@ -58,7 +58,8 @@
         "System.Reflection.TypeExtensions": "4.1.0-*",
         "System.Text.RegularExpressions": "4.0.11-*",
         "System.Threading": "4.0.11-*",
-        "System.Threading.ThreadPool": "4.0.10-*"
+        "System.Threading.ThreadPool": "4.0.10-*",
+        "System.Collections.NonGeneric": "4.0.1-*"
       }
     }
   }

Dapper/DynamicParameters.CachedOutputSetters.cs

@@ -8,11 +8,7 @@ partial class DynamicParameters
     {
         internal static class CachedOutputSetters<T>
         {
-#if COREFX
-            public static readonly Dictionary<string, Action<object, DynamicParameters>> Cache = new Dictionary<string, Action<object, DynamicParameters>>();
-#else
             public static readonly Hashtable Cache = new Hashtable();
-#endif
         }
     }
 }

Dapper/DynamicParameters.cs

@@ -400,15 +400,7 @@ public DynamicParameters Output<T>(T target, Expression<Func<T, object>> express
             var lookup = string.Join("|", names.ToArray());
 
             var cache = CachedOutputSetters<T>.Cache;
-            Action<object, DynamicParameters> setter;
-#if COREFX
-            lock (cache)
-            {
-                if(!cache.TryGetValue(lookup, out setter)) setter = null;
-            }
-#else
-            setter = (Action<object, DynamicParameters>)cache[lookup];
-#endif
+            Action<object, DynamicParameters> setter = (Action<object, DynamicParameters>)cache[lookup];
             if (setter != null) goto MAKECALLBACK;
 
             // Come on let's build a method, let's build it, let's build it now!

Dapper/SqlMapper.cs

@@ -2282,23 +2282,15 @@ static readonly MethodInfo
         public static ITypeMap GetTypeMap(Type type)
         {
             if (type == null) throw new ArgumentNullException(nameof(type));
-#if COREFX
-            ITypeMap map = null;
-#else
             var map = (ITypeMap)_typeMaps[type];
-#endif
             if (map == null)
             {
                 lock (_typeMaps)
                 {   // double-checked; store this to avoid reflection next time we see this type
                     // since multiple queries commonly use the same domain-entity/DTO/view-model type
-#if COREFX
-                    if (!_typeMaps.TryGetValue(type, out map)) map = null;
-#else
                     map = (ITypeMap)_typeMaps[type];
-#endif
 
-                        if (map == null)
+                    if (map == null)
                     {
                         map = TypeMapProvider( type );
                         _typeMaps[type] = map;
@@ -2309,11 +2301,7 @@ public static ITypeMap GetTypeMap(Type type)
         }
 
         // use Hashtable to get free lockless reading
-#if COREFX
-        private static readonly Dictionary<Type,ITypeMap> _typeMaps = new Dictionary<Type, ITypeMap>();
-#else
         private static readonly Hashtable _typeMaps = new Hashtable();
-#endif
 
         /// <summary>
         /// Set custom mapping for type deserializers

Dapper/project.json

@@ -56,7 +56,8 @@
         "System.Reflection.TypeExtensions": "4.1.0-*",
         "System.Text.RegularExpressions": "4.0.11-*",
         "System.Threading": "4.0.11-*",
-        "System.Threading.ThreadPool": "4.0.10-*"
+        "System.Threading.ThreadPool": "4.0.10-*",
+        "System.Collections.NonGeneric": "4.0.1-*"
       }
     }
   }