Built-in Functions

Bop provides 11 built-in functions available in every program. These cannot be shadowed by user-defined functions.

Output

print(args...)

Prints values to output, separated by spaces. Returns none.

print("hello")           // hello
print("x =", 42)         // x = 42
print(1, "plus", 2)      // 1 plus 2

print accepts any number of arguments (including zero). Each argument is converted to its string representation automatically.

inspect(value)

Returns a debug representation of a value as a string. Strings are wrapped in quotes; other types look the same as str().

print(inspect("hello"))    // "hello"
print(inspect(42))         // 42
print(inspect([1, 2]))     // [1, 2]

Useful for debugging when you need to distinguish strings from other types.

Type Conversion

str(value)

Converts any value to its string representation.

str(42)        // "42"
str(3.14)      // "3.14"
str(true)      // "true"
str(none)      // "none"
str([1, 2])    // "[1, 2]"

int(value)

Truncates a number to an integer, or parses a string as a number and truncates.

int(3.9)       // 3
int(-2.7)      // -2
int("42")      // 42
int(true)      // 1
int(false)     // 0

Produces an error if the value can’t be converted (e.g., int("hello")).

type(value)

Returns the type name of a value as a string.

type(42)           // "number"
type("hello")      // "string"
type(true)         // "bool"
type(none)         // "none"
type([1, 2])       // "array"
type({"a": 1})     // "dict"

Math

abs(x)

Returns the absolute value of a number.

abs(-5)     // 5
abs(3)      // 3
abs(-2.7)   // 2.7

min(a, b)

Returns the smaller of two numbers.

min(3, 7)      // 3
min(-1, -5)    // -5

max(a, b)

Returns the larger of two numbers.

max(3, 7)      // 7
max(-1, -5)    // -1

rand(n)

Returns a random integer from 0 to n-1 (inclusive). The argument must be a positive integer.

rand(6)     // 0, 1, 2, 3, 4, or 5
rand(2)     // 0 or 1 (coin flip)
rand(100)   // 0 to 99

Note: rand uses a deterministic pseudo-random number generator. The same seed produces the same sequence of values.

Collections

len(value)

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

len("hello")       // 5
len([1, 2, 3])     // 3
len({"a": 1})      // 1
len("")            // 0
len([])            // 0

Produces an error for numbers, bools, and none.

Ranges

range(n) / range(start, end) / range(start, end, step)

Generates an array of numbers.

range(5)           // [0, 1, 2, 3, 4]
range(2, 6)        // [2, 3, 4, 5]
range(0, 10, 2)    // [0, 2, 4, 6, 8]
range(5, 0)        // [5, 4, 3, 2, 1]  (auto-detects direction)
range(10, 0, -3)   // [10, 7, 4, 1]

• With 1 argument: range(n) produces [0, 1, ..., n-1]
• With 2 arguments: range(start, end) auto-detects direction
• With 3 arguments: range(start, end, step) uses the given step (error if step is 0)
• Maximum 10,000 elements