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Declaring Functions

Functions​

A function is a construct that accepts input and returns output, executing the expressions or statements within it.

New functions are declared using the function keyword.

At least 1 parameter must be declared, and each parameter must have a data type declared after its name. The return type must also be included in the function declaration.

note

The last expression of a function is implicitly returned.

Syntax

function NAME( PARAMETERS ) -> RETURN TYPE { BODY; }

Example

Declare a function named square which returns x * x:

flex
function square(x : float64) -> float64 {
    x * x;
}

Variables​

Variables may be declared within the scope of a function using the let keyword.

Syntax

let NAME = EXPRESSION;

Example

Declare a variable named sq that is equal to x * x:

flex
function squarePlusOne(x : float64) -> float64 {
	let sq = x * x;
	sq + 1.0;
}

The last expression sq + 1.0 is returned.

Conditional Statements​

Conditional statements may be included using the if, else if, and else keywords.

Syntax

if ( TEST EXPRESSION ) { THEN STATEMENTS; } else { ELSE STATEMENTS; }

Example

Declare a function named AntiqueOrVintage which returns a string conditionally based upon an age parameter:

flex
function AntiqueOrVintage(age : uint8) -> string {
    if (age >= 100) {
        "Antique";
    } else if (age >= 40) {
        "Vintage";
    } else {
        "Neither";
    };
}

The braces can be omitted for singe line statements:

flex
function AntiqueOrVintage(age : uint8) -> string {
    if (age >= 100) "Antique" else if (age >= 40) "Vintage" else "Neither";
}

Built-in Functions​

length​

length(x) Return the length of x where x is an array.

flex
function length(x : Array) -> int32

floor​

floor(x) Return the floor of x where x is a float64.

flex
function floor(x : float64) -> float64

float64to32​

float64to32(x) Return the 32 bit version of x where x is a float64.

flex
function float64to32(x : float64) -> float32

sin​

sin(x) Return the sine of x where x is a float64 in radians.

flex
function sin(x : float64) -> float64

cos​

cos(x) Return the cosine where x is a float64 in radians.

flex
function cos(x : float64) -> float64

tan​

tan(x) Return the tangent where x is a float64 in radians.

flex
function tan(x : float64) -> float64

sqrt​

sqrt(x) Return the square root of x where x is a float64.

flex
function sqrt(x : float64) -> float64

pow​

pow(x,y) Return x raised to the power of y where x and y are both float64.

flex
function pow(x : float64, y : float64) -> float64

some​

some(x) Constructor for an option that has a value x. Used with optional data types, and pattern matching. For more details see Pattern Matching > Some and None

getOrElse​

getOrElse(x,y) Return x if it is present, or a default value y when it's not present. Used with optional data types, and value casting. For more details see Value Casting.