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--- codesnippets:typeclasses [2021/04/10 17:23] – f2b216
+++ codesnippets:typeclasses [2025/10/08 00:48] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Type classes and its instances, and the deriving mechanism ======
-~~DISCUSSION~~
   * A type class (keyword: ''class'') is a set of functions declarations that
@@ Line 6: / Line 5: @@
     * have instances (keyword: ''instance'') with type specific bindings.
   * module ''Prelude'' already consists of many type classes
-    * {{:codesnippets:preludetypeclasses.png?400|Type classes in Prelude}}
+    * {{:modules:preludetypeclasses.png?direct&300|}}
+      * picture from: Dirk Hünniger
+      * source: [[https://commons.wikimedia.org/wiki/File:HaskellClasses.svg]]
       * type ''class''es are in bold
       * below all types that have implemented instances
@@ Line 14: / Line 15: @@
         *'' Float''
         * ''Double''
+  * additionally, there is many other libraries available with important type classes
+    * {{:codesnippets:typeclassopedia-diagram.png?direct&700|}}
+      * source: [[https://wiki.haskell.org/Typeclassopedia]]
   * example, implementing an ''Enum'' type class, and an instance for a data type
     * functions ''succ'', and ''pred'' have default implementations in ''class  Enum'',
@@ Line 97: / Line 101: @@
 ===== Deriving mechanism =====
-Looking to the examples above you may wonder, whether there a better way to implement instance of standard type classes. Yes, there is the deriving mechanism.
+Looking to the examples above you may wonder, whether there an easier way to implement an ''instance'' of standard type classes. Yes, there is the ''deriving'' mechanism.
-  * example, data type applies ''deriving'' mechanism
+  * example, where a data type applies ''deriving'' mechanism
     * to implement all function of typeclass ''Show'', and ''Enum''
     * code:<code Haskell>
@@ Line 116: / Line 120: @@
 ===== Advanced type classes =====
-  * example, implementing a ''Functor'':<code Haskell>
+  * example, implementing a ''Functor''
+    * code:<code Haskell>
 import Prelude hiding (Maybe(..), Functor(..))
@@ Line 140: / Line 145: @@
 </code>
+===== ✎ =====
+~~DISCUSSION~~