Chapter 8

Chapter 8

1. Algebraic data types

   • Define our own data types
   • using the word "data"
     • means that a new data type is being defined
   • It is necessary to write the data type name
   • Value constructors
     • Defines the values that can take the data type that is going to be defined
   • Example
     • data Bool = True | False

2. Record syntax

   • Modules can define data types aswell
     • To be more simple to understand and read it is used record syntax
       • Works the same way as the algebraic data types, the only difference is that it's more readable
       • Record syntax works like object oriented prgramming
         • We define the attributes and their data types

3. Type parameters

   • Instead of having values as parameters we have data types as parameters
   • For example
     • data Maybe a = Nothing | Just a
       • "a" is a type parameter
         • the result could be Just Int or Just Char

4. Derived instances

   • It is used to implement a behaviour in a new data type
     • To do so it is necessary to use the word "Deriving"
       • And then write the typeclass we want to implement
       • For example: deriving (Eq, Show, Read)

5. Type synonims

   • Give types a different name
     • For example [Char], its type synomim would be String

6. Typeclasses 102

   • As we can define modules, we can also define our own typeclasses
     • To define a new typeclass we use the word "class" followed by the name and then "where"
       • class Eq a where