Simple types

The type of a variable delineates the set of values it can hold. In this document, you will learn about the different simple types a Flow variable can have.

number

The number type can hold hold numeric values, including both integers and floating-point. Number values are written in decimal representation, using the point character to separate the integer and fractional parts.

// Example: Create three variables of type number
let x = 1 + 2;
let y = 0.5;
let z = -1;

Advanced: Representation of numbers

Under the hood, numbers are represented in 128-bit decimal floating-point format as defined in IEEE 754-2008. This gives them a relatively high accuracy, a range of approximately ±1.0 × 10⁻²⁸ to ±7.9228 × 10²⁸, and a precision of 28-29 digits.

text

The text type, known as "string" or "varchar" in other languages, can hold variable-length sequences of Unicode characters. Literal text values can be written using either single or double quote characters.

A text literal that begins with a double quote may contain single quote characters. The converse is also true.

// Example: Declare two variables of type text
let country = "Netherlands";
let city = 'Rotterdam';

A literal surrounded by the backquote (`) character is known as a template literal. In a template literal, expressions can be inserted within curly braces.

// Example: A template literal

let country = "Japan";

return `The name of the country is {country}.`;
// returns "The name of the country is Japan."

Template literals, unlike single and double quoted literals, may also contain line breaks.

Advanced: Special characters in literals

Some characters such as line feeds and backspaces must be inserted into the literal by means of an escape sequence. An escape sequence is formed by a backslash character followed by one or many escape sequence characters. For example, if you want to specify a text literal representing several lines of text, the escape sequence \n can be used to insert a line feed character: "first line\nsecond line". Similarly, the double quote character can be inserted into a double quote-delineated text literal by means of the \" escape sequence. For a full list of supported escape sequences, refer to the Appendix on escape sequences.

Advanced: Verbatim literals

When working with Regular expressions, it often useful not to have FlowScript interpret backslashes as escape sequences. In those cases, you can prefix the literal by the @ sign, creating a verbatim literal.

// The @ character creates a verbatim literal
// where backslashes are not interpreted as escape sequences.
let pattern = @"\w+"; 

boolean

The boolean type represents a truth value. A variable of type boolean can only be assigned the values true or false.

// Example: Declare two variables of type boolean
let x = true;
let y = false;

Boolean values are often used in conjunction with boolean operators.

datetime

The datetime type represents a calendar date and time of day. Unlike numbers, texts and booleans, datetime values have no special literal syntax. Instead, you typically receive them from a Date input, or work with them programmatically using the now function, the date function or any of the functions in the DateTime module.

// Example: Declare a variable of type datetime
let currentDateAndTime = now();

binary

The binary type represents unintepreted variable-length binary data such as an image, an encoded block of text or a PDF document. Binary variables typically orignate from a File gallery or the HTTP module. There is no literal syntax for binary values.

primitive

A value with the primitive type may be either number, text, boolean, datetime, binary or null. Type checking is relaxed for such values: you can freely use a value of type primitive in any situation where a number, text, boolean, etc. is called for. However, the actual value must be compatible with the requested type, or the application will fail at runtime.

// Example: create a function which calculates the square of a number.
// Then, pass two values of type primitive into it. The second call will fail.

function square(x: number) => x * x;

let x: primitive = "1";
let y: primitive = "this is definitely not a number";

// ERROR: This will fail because "y" cannot be converted to a number.
return square(x) + square(y);