Built-in Functions

These functions are built into the language and always available — no imports needed.

Program Control

exit()

(int) -> void

Exits the program with the specified status code.

// Exit with success
exit(EXIT_SUCCESS)

// Exit with failure
exit(EXIT_FAILURE)

// Exit with custom code
exit(42)

Parameters: An integer status code (0 for success, non-zero for failure).

Returns: Does not return (terminates the program).

panic()

(string) -> void

Terminates the program immediately with a panic message. The message is prefixed with [PANIC].

panic("something went wrong")
// Output: [PANIC] something went wrong

Parameters: A string message describing why the program is panicking.

Returns: Does not return (terminates the program).

assert()

(bool, string) -> void

Checks that a condition is true. If the condition is false, terminates the program with an assertion failure message prefixed with [ASSERT].

temp x int = 5
assert(x > 0, "x must be positive")  // Passes

temp y int = -1
assert(y > 0, "y must be positive")  // Fails: [ASSERT] y must be positive

Parameters:

• condition: A boolean expression to check
• message: A string message to display if the assertion fails

Returns: Nothing if the condition is true; terminates the program if false.

Constants

EXIT_SUCCESS

int constant with value 0

Represents a successful program exit.

exit(EXIT_SUCCESS)  // Exit with code 0

EXIT_FAILURE

int constant with value 1

Represents a failed program exit.

exit(EXIT_FAILURE)  // Exit with code 1

Utility Functions

input()

() -> string

Reads a line of text from stdin.

import @std

std.print("Enter your name: ")
temp name string = input()
std.println("Hello, " + name)

read_int()

() -> (int, Error)

Reads an integer from stdin. Returns a tuple of the parsed integer and an error (if the input cannot be parsed).

import @std

std.print("Enter a number: ")
temp num, err = read_int()

if err != nil {
    std.println("Invalid input: " + err.message)
} otherwise {
    std.println("You entered: " + string(num))
}

len()

(value) -> int

Returns the length of a string, array, or map.

import @std

temp name string = "Hello"
std.println(len(name))  // 5

temp nums [int] = {1, 2, 3}
std.println(len(nums))  // 3

temp ages map[string:int] = {"Alice": 30, "Bob": 25}
std.println(len(ages))  // 2

range()

Generates a sequence of numbers for for loops.

import @std

// range(start, end) - end is exclusive
for i in range(0, 5) {
    std.println(i)  // 0, 1, 2, 3, 4
}

// range(start, end, step)
for i in range(0, 10, 2) {
    std.println(i)  // 0, 2, 4, 6, 8
}

typeof()

(value) -> string

Returns the type of a value as a string.

import @std

temp x int = 42
std.println(typeof(x))  // "int"

temp arr [string] = {"a", "b"}
std.println(typeof(arr))  // "array"

copy()

(value) -> value

Creates a deep copy of a value. Since EZ uses copy-by-default semantics, this function is primarily useful when you want to be explicit about copying.

const Person struct {
    name string
    age int
}

temp a Person = Person{name: "Alice", age: 30}
temp b Person = copy(a)  // Explicit copy (same as just `temp b = a`)
b.age = 31
// a.age is still 30 - b is an independent copy

Note: With copy-by-default behavior, temp b = a already creates an independent copy. Use copy() when you want to be explicit about your intent, or use ref() when you need shared data.

Deep copy behavior:

• Primitives return themselves
• Nested structs are recursively copied
• Arrays are copied with all elements
• Maps are copied with all key-value pairs

ref()

(value) -> reference

Creates a reference to a value, enabling shared data between variables. Use this when multiple variables need to point to the same underlying data.

const Person struct {
    name string
    age int
}

temp a Person = Person{name: "Alice", age: 30}
temp b Person = ref(a)  // b references the same data as a
b.age = 31
// a.age is now 31 - both variables share the same data

When to use ref():

• When multiple variables need to share and modify the same data
• When passing large data structures without copying overhead
• When you need changes in one place to be visible everywhere

Works with all types:

• Primitives (int, float, string, bool, char)
• Complex types (structs, arrays, maps)

// Reference to an array
temp original [int] = {1, 2, 3}
temp shared [int] = ref(original)
shared[0] = 100
// original[0] is now 100

// Reference to a primitive
temp count int = 0
temp counter int = ref(count)
counter++
// count is now 1

Note: Without ref(), assignments create independent copies by default.

new()

(StructType) -> StructType

Creates a new instance of a struct with all fields set to their zero values.

const Person struct {
    name string
    age int
    active bool
}

temp p Person = new(Person)
// p.name = ""
// p.age = 0
// p.active = false

Zero values by type:

• string → ""
• int, float → 0
• bool → false
• char → '\0'
• Arrays → empty array
• Maps → empty map

Type Conversion Functions

Convert values between types. These are essential for working with user input, formatting output, and data transformations.

cast()

(value, type) -> value

Converts a value to the specified type. Unlike other conversion functions, cast() accepts any valid EZ type as its second argument, including sized integers and array types.

// Single value conversion
temp x = cast(42, u8)        // int -> u8
temp y = cast(3.14, int)     // float -> int
temp z = cast(65, char)      // int -> char

// Array element-wise conversion
temp bytes [byte] = {65, 66, 67}
temp u8_arr = cast(bytes, [u8])  // [byte] -> [u8]

temp nums [int] = {1, 2, 3}
temp strs = cast(nums, [string])  // ["1", "2", "3"]

Parameters:

• value — The value or array to convert
• type — Target type (e.g., u8, int, string, [u8])

Returns: The converted value in the target type.

Error handling: Invalid conversions produce errors with details:

temp result = cast([-1, 2, 3], [u8])
// Error: "cast failed at index 0: value -1 out of u8 range (0 to 255)"

Note: cast() is technically a language keyword because the type argument is validated at check-time (before execution). See also: cast in Keywords.

int()

(value) -> int

Converts a value to an integer.

temp s string = "42"
temp n int = int(s)  // 42

temp f float = 3.9
temp i int = int(f)  // 3 (truncates)

float()

(value) -> float

Converts a value to a float.

temp n int = 42
temp f float = float(n)  // 42.0

temp s string = "3.14"
temp pi float = float(s)  // 3.14

string()

(value) -> string

Converts a value to a string.

temp n int = 42
temp s string = string(n)  // "42"

temp b bool = true
temp bs string = string(b)  // "true"

char()

(int) -> char

Converts an integer (ASCII/Unicode value) to a character.

temp x int = 65
temp c char = char(x)  // 'A'

temp newline char = char(10)  // newline character

byte()

(int) -> byte

Converts an integer to a byte (constrained to 0-255).

temp n int = 65
temp b byte = byte(n)  // 65

temp max byte = byte(255)  // 255
temp wrapped byte = byte(256)  // Error: value out of range

Behavior:

• Values 0-255 convert directly
• Values outside 0-255 range produce an error
• Useful when working with the @bytes module

Error Handling

Error Type

The Error type represents an error value that can be returned from functions.

Checking for errors:

temp err = validate("")
if err != nil {
    println("Error: ${err.message}")
}

error()

(string) -> Error

Creates a user-defined error. Returns an Error with .message set to the argument and .code set to empty string.

Single error return:

do validate(name string) -> Error {
    if len(name) == 0 {
        return error("name cannot be empty")
    }
    return nil
}

do main() {
    temp err = validate("")
    if err != nil {
        println(err.message)  // "name cannot be empty"
    }
}

Tuple return (value + error):

do divide(a int, b int) -> (int, Error) {
    if b == 0 {
        return 0, error("division by zero")
    }
    return a / b, nil
}

do main() {
    temp result, err = divide(10, 0)
    if err != nil {
        println("Failed: ${err.message}")
    } otherwise {
        println("Result: ${result}")
    }
}

Quick Reference

Functions

Constants