learnyousomeerlang, erlang

learnyouerlang.md

installation

brew install erlang

Tuple datastructure

Tuples are datastructure to store sequence of multiple data which could be of different types.

lets define inventoty as sequence of Item, Qty, UnitPrice

27> ShirtInventory = {"shirts", 100, 88}.
{"shirts",100,88}

ifdef(comment).
   pattern match
-endif.
28> {Item, Qty, UnitPrice} = ShirtInventory.
{"shirts",100,88}
29> Item.
"shirts"

List datastructure

a sequence of data of same/different types, unlike tuples can have unknown number of elements in it. has head and tail.

7> [1, 3, 5, 7] ++ [11, 13, 17, 19].
[1,3,5,7,11,13,17,19]

1> FibList = [1, 1, 2, 3, 5].
[1,1,2,3,5]

2> AnotherFibList = [0 | FibList].
[0,1,1,2,3,5]

#list pattern match

4> [Head|Tail] = AnotherFibList.
[0,1,1,2,3,5]
522> Head.
0
5> Tail.                             
[1,1,2,3,5]

6> [H | T] = Tail.
[1,1,2,3,5]
25> H.
1
7> T.
[1,2,3,5]

List comprehension - ways to build or modify lists.

[0.85*Price || Price <- [100,200,300,400]].

## get discounted prices for items in cart

2> Cart = [{"nexus", 100},{"woofer", 200},{"mic", 300},{"Drum", 400}]. 
[{"nexus",100},{"woofer",200},{"mic",300},{"Drum",400}]

3> [0.85*Price || {Item, Price} <- Cart].
[85.0,170.0,255.0,340.0]

http://learnyousomeerlang.com/starting-out-for-real#numbers