

Built-in types

Introduction

Pineapple has special support for the following types:

• Boolean

• Nil (also known as null)

• Number and Integer

• String

• List (also known as array)

• Tuple (also known as array)

• Table (also known as Dictionary or HashMap)

---

Boolean

Boolean types in Pineapple can be declared using #true and #false.

let isHappy = #true
let isSad   = #false

Boolean type is necessary for using control statements such as if-else or while loop.

For example,

let isMad = #true

if isMad
    "Oh my goodness".show
else
    "Thank goodness".show

---

Nil

Nil type is useful when you are not sure what to assign for a variable.

let car = #nil // This means that you dont have a car

Note

By default, you cannot assign #nil to any variable. Check out Variables for more information.

---

Number and Integer

let x = 123 // Will be inferred as Integer
let y = 123.4 // Will be inferred as Number

Info

Integer is any number that do not contains decimal values. It is especially useful for counting things, for example numberOfFruits should be Integer instead of Number.

---

String

In Pineapple, strings are enquoted using double quotes.

let message = "Hello world"

String interpolation

You can also interpolate expressions into string using $().

let fruit = "Pineapple"
let howMany  = 5 + 9

let message = "I like to eat $(fruit) every $(howMany.toString) days"

message.show // I like to eat Pineapple 5 days

Note

Every interpolated expression must have type of String, if not the Pineapple compiler will complain about it.

For example,

let x = 23.4
let message = "My number is $(x)" // Error, `x` should be String, but it is Number

To prevent such problem, you have to use the .toString function.

Warning

Interpolated expression cannot be raw string. For example,

let y = "$("yo")" // Syntax error

---

List

List are useful for storing more than one elements. To create a list in Pineapple, you need to use square brackets [ ] and comma , .

// Create list of integers
let xs = [1,2,3,4]

// You can pass in any expression as element
let x = 99
let numbers = [.pi, 3 + 3, 7.square, x]

List in Pineapple are homogeneous, it means that all elements within a list must be the same type. For example,

let x = [1, "2"] // Error, the second element should be Integer

Warning

You cannot create an empty list by using []. Instead you need to use the List constructor.

let xs = [] // error

let ys = List{Integer} // No error

Multiline List

Sometimes your list might contains too many elements to be fit in a single line. In such situation you will need to use multiline list. For example,

let fruits =
    o "Apple"
    o "Banana"
    o "Pineapple"
    o "Durian"
    o "Hello"

Note

The indentation is necessary. So, the following is invalid in Pineapple:

let fruits = 
o "Apple"
o "Banana"
// Error

Reminder

Since o is used as list bullet in Pineapple, you cannot named a variable as o.

---

Table

Table is also known as Dictionary or HashMap. It is useful when you need to store a list of key-value data.
For example, let say you want to store phone numbers:

// note that the indentation is necessary
let phoneNumbers =
    "john" = "0123456"
    "babe" = "3333222"
    "wong" = "3212344"
    "lee"  = "9843056"

phoneNumbers.("john").show // "0123456"

Empty table

To create an empty table, use the Table constructor.

                        // key , value
let phoneNumbers = Table{String, String}

Comments