starting out

starting out

1. infix functions

   • 5*5
   • 5/5
   • 5+5
   • 5-5
   • explicit precedence: ()
   • function has the higher precedence

2. prefix functions

   • as infix function
     • 92 `div` 10
   • calling
     • name argument argument
       • succ 8
       • max 6.0 7.5
       • min 5 6
   • creating
     • functionName [parameters..] = <what the function does>
       • doubleUs x y = x*2 + y*2
         • doubleUs 4 9
         • different version?
           • doubleUs'
       • No parameters?
         • name || definition
     • Is their order important in .hs file?
       • No

3. boolean algebra

   • &&
   • ||
   • not
   • True
   • False

4. in(equality)

   • ==
   • /=

5. expression

   • a piece of code that returns a value
     • like
       • if statement
         • if <condicion> then <..> else <..>
           • else is mandatory
             • so, makes the if an expression

6. List

   • [1,2, 3]
   • homogenous data structure
   • Strings
     • ['h', 'a', 's']
   • [3,4,5]
   • concatenation
     • ++
       • [1,2,3] ++ [4,5,6]
   • add element at head ?
     • 0 : [1,2,3]
       • [0,1,2,3]
   • [[],[],[]]
     • must be of equal type!!
   • need at element?
     • [] !! <index>
   • are comparable in lexicographical order.
     • [3,2,1] > [2,1,0]
       • True
   • Ranges
     • [1..5]
     • ['a'..'z']
     • with steps
       • [2,4..20]
       • [20,19..1].
       • [13,26..24*13]
     • works well with float-point?
       • No, precision-lost
   • Common functions
     • head
   • infinite?
     • cycle
     • repeat
   • comprehensions
     • [x*2 | x <- [1..10]
       • with predicates || filtering
         • [x*2 | x <- [1..10], x*2 >= 12]
     • like in math
       • S = {2X | x E N, x <= 10}
   • of
     • should be of equal size
       • [(1,2),(8,11,5),(4,5)]
         • Error!!

7. Tuples

   • pair
     • (1,2)
   • heterogenous data structure
   • triple
     • (1,"Two",3)
   • some functions
     • fst
       • fst (1,2)
         • 1
     • snd
       • snd (1,2)
         • 2
     • zip
       • zip [1,2] [3,4]
         • [(1,3), (2,4)]