Higher-Order Functions

Higher-Order Functions

1. Three Possibilities

   • Take functions as parameters
   • Return functions as parameters
   • Both

2. Curried Functions

   • By applying a space between two things
   • Space considered as an operator
     • Separated by arrows ->
   • Partially Applied Functions
     • Take the parameters you need
   • Infix functions
     • Parentheses plus parameter

3. Associations and Filters

   • The function is taken and applied to each element
   • Something new is produced
   • Predicates
     • If it is true, it is included
   • Map and Filter
     • One time only
       • It is trimmed according to need
     • Lists by Compression

4. Lambdas

   • Anonymous function
     • It is only needed once
     • To pass it to higher order function
   • The sign \
     • Parameters separated by space
       • It is created: \ ... -> (...)
   • Expressions
     • They take any number of parameters

5. Folds

   • Reduce lists to a single value
     • Binary calls Accumulator
       • So on
       • It can be of any type
   • Take a binary function
     • An Initial Value or Accumulator
       • List to fold
   • To the left
     • Finite
   • To the right
     • Infinite

6. $ Function

   • Order of low precedence
   • Associative on the right
   • Replace Parenthesis

7. Composition of Functions

   • They must have the same type of parameter
   • Point Free Style
     • Pass values easily