Fmt Module Documentation

The fmt module provides type conversion, type detection, string formatting, and number representation utilities.

Usage

use fmt;

fmt.to_int("42");        // 42
fmt.to_str(3.14);        // "3.14"
fmt.type(true);          // "bool"
fmt.is_string("hello");  // true
fmt.to_hex(255);         // "ff"
fmt.pad_left("5", 3, "0"); // "005"

Type Conversion

fmt.to_int(value)

Converts to integer (truncates decimals).

Input	Output
42.7	42
"123"	123
true	1
nil	0
array/object/function	throws

fmt.to_float(value)

Converts to floating-point number.

Input	Output
42	42
"3.14"	3.14
true	1.0
nil	0.0

fmt.to_str(value)

Converts to string.

Input	Output
42	"42"
true	"true"
nil	"nil"
"hi"	"hi"

fmt.to_bin(value)

Converts integer to binary string (no leading zeros).

fmt.to_bin(10);    // "1010"
fmt.to_bin(255);   // "11111111"
fmt.to_bin(true);  // "1"
fmt.to_bin(0);     // "0"

Type Detection

fmt.type(value)

Returns the type name as a string: "nil", "bool", "number", "string", "function", "object", "array", "module".

Type Predicates

All take one argument and return a boolean.

Function	Returns true when
fmt.is_int(v)	value is a number with no fractional part
fmt.is_float(v)	value is any number
fmt.is_string(v)	value is a string
fmt.is_bool(v)	value is a boolean
fmt.is_nil(v)	value is nil
fmt.is_array(v)	value is an array

Note: fmt.is_int and fmt.is_float both require a number type — is_int additionally checks that the value has no fractional part.

fmt.is_int(42);     // true
fmt.is_int(42.5);   // false
fmt.is_float(42.5); // true
fmt.is_float("x");  // false

Number Formatting

fmt.to_hex(n)

Returns lowercase hex string of integer n.

fmt.to_hex(255);   // "ff"
fmt.to_hex(16);    // "10"
fmt.to_hex(0);     // "0"

fmt.to_oct(n)

Returns octal string of integer n.

fmt.to_oct(8);    // "10"
fmt.to_oct(255);  // "377"

String Padding

fmt.pad_left(str, width, char?)

Pads str on the left to reach width. Default pad char is space.

fmt.pad_left("42", 5);       // "   42"
fmt.pad_left("42", 5, "0");  // "00042"

fmt.pad_right(str, width, char?)

Pads str on the right to reach width.

fmt.pad_right("hi", 5);      // "hi   "
fmt.pad_right("hi", 5, "-"); // "hi---"

If str is already at or beyond width, it's returned unchanged.

Examples

use fmt;

// Zero-pad a number for display
var id = fmt.pad_left(fmt.to_str(7), 4, "0"); // "0007"

// Hex dump style
var hex = fmt.to_hex(255); // "ff"

// Safe type check before math
if (fmt.is_float(userInput)) {
    var result = userInput * 2;
}

// Dynamic dispatch by type
fun describe(v) {
    say(fmt.type(v) + ": " + fmt.to_str(v));
}