Making Our Own Types and Typeclasses

Making Our Own Types and Typeclasses

1. Algebraic data types

   • use the data keyword to define a type
     • means that we're defining a new data type.
     • has to have constructor attributes
     • some data types Bool, Int, Char, Maybe
   • Representation of a shape in haskell
     • tuples
     • could also represent a 3D vector or anything else
     • make our own type to represent a shape
       • can optionally add some types after it and those types define the values it will contain
       • can also export data types in diferent modules

2. Record syntax

   • define what information wan to record
     • set the data type
     • use curly brackets
       • write a double colon
         • specify the type
           • creates functions that lookup fields in the data type

3. Type parameters

   • can take some values parameters and then produce a new value
   • can take types as parameters to produce new types
   • can make different types with them depending on what kind of types we want contained in our data type

4. Derived instances

   • Haskell can automatically make our type an instance of any of the following typeclasses
   • Haskell can derive the behavior of the types

5. Type synonyms

   • they do nothing by itself
   • gave some types different names so that they make more sense to someone reading our code and documentation