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Built-in Functions

Radon exposes a fixed set of interpreter built-ins. The list below reflects the functions currently registered in core/builtin_funcs.py.

Console and Flow Control

  • print(value) prints a value.
  • print_ret(value) returns the string form of a value.
  • input(prompt) reads a line of input.
  • input_int() reads an integer and keeps prompting until the input is valid.
  • clear() clears the terminal.
  • cls() is an alias for clear().
  • exit() stops the current program.

Introspection

  • len(value) returns the length of a value when supported.
  • type(value) returns the Radon type wrapper for a value.
  • help(obj) prints the help representation of an object.
  • dir(obj) returns an array of visible names on a module or class-like object.

Type Conversion

  • int(value) converts a value to an integer.
  • float(value) converts a value to a float.
  • str(value) converts a value to a string.
  • bool(value) converts a value using Radon's truthiness rules.

Type Checks

  • is_num(value) returns whether the value is a number.
  • is_int(value) returns whether the value is an integer number.
  • is_float(value) returns whether the value is a floating-point number.
  • is_str(value) returns whether the value is a string.
  • is_bool(value) returns whether the value is a boolean.
  • is_array(value) returns whether the value is an array.
  • is_fun(value) returns whether the value is a function.
  • is_null(value) returns whether the value is null.

Runtime and Interop

  • require(module) executes a standard library module name or a .rn file path.
  • pyapi(code, ns) executes Python code with a Radon hash map used as the namespace bridge.
  • time_now() returns the current Unix timestamp.

pyapi() is permission-gated at runtime.

Shell Helpers

  • license() prints the project license.
  • credits() prints the project credits.
  • copyright() prints the copyright banner.

Command-Line Arguments

Radon does not expose a sys_args() built-in. The CLI stores process arguments in the global argv array before running user code.

argv.rn
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for arg in argv {
    print(arg)
}

Built-in Classes

The following class constructors are pre-loaded into the global scope without any import.

File(path, mode)

Opens a file. Requires disk_access permission. Modes: "r" read, "w" write, "a" append. See the file-handling guide for full usage.

String(value)

Wraps a string with chainable helper methods (len(), find(), join(), to_int(), etc.). Identical to the object provided by import string.

Json

Serialises and deserialises JSON. Can be used statically or as an instance:

json.rn
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const text = Json.dumps({"key": "value"})
const data = Json.loads(text)
print(data["key"]) # value

Requests

HTTP client. Requires network_access permission.

requests.rn
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var res = Requests.get("https://api.example.com/data")
print(res.status_code)
print(res.text)

builtins

Provides access to the built-in scope as an object. Used for reflection and tooling; not normally needed in application code.

Primitive Methods

All primitive types (Array, String, Number, Boolean, HashMap) support objective method syntax via dot notation. Methods are called directly on values without needing any imports.

primitive_methods.rn
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# Array methods
var arr = [1, 2, 3]
arr.append(4)           # [1, 2, 3, 4]
arr.length()            # 4
arr.pop()               # removes and returns 4

# String methods
var s = "hello world"
s.upper()               # "HELLO WORLD"
s.split(" ")            # ["hello", "world"]
s.length()              # 11

# Number methods
var n = 42
n.is_even()             # true
n.sqrt()                # 6.48...
(-5).abs()              # 5

# Boolean methods
var b = true
b.toggle()              # false
b.to_string()           # "true"

# HashMap methods
var hm = {"a": 1, "b": 2}
hm.keys()               # ["a", "b"]
hm.has("a")             # true

For complete method references, see: