Data types

Mélodium have multiple core data types, shared across four main categories, plus bool, byte and void:

  • unsigned integers
  • signed integers
  • floating-point numbers
  • textual data

All those types are described across their respective section. Each type has been selected because it meets a very specific purpose.

Unsigned integersSigned integersFloating-point numbersTextLogic
u8i8f32charbyte
u16i16f64stringbool
u32i32void
u64i64
u128i128

Byte

TypeValuesSize
byteAny 8-bits data8 bits / 1 byte

A byte is basically the most atomic unit of data manipulable through Mélodium. It represents any 8-bits data, without more assumption on what it could be.

Bool

TypeValuesSize
booltrue or false8 bits / 1 byte

A bool is a boolean value that can be either set to true or false. Conversion treatments are available for bools to be turned into bytes, numbers, or any kind of value.

Void

TypeValuesSize
voidNone0 bit / 0 byte

void data type does not hold any value, it just indicates that something is existing. It is used through connections to transmit triggers or streaming indicators.

Unsigned integers

TypeRangeSize
u80 to 2⁸-1 (255)8 bits / 1 byte
u160 to 2¹⁶-1 (65,535)16 bits / 2 bytes
u320 to 2³²-1 (4,294,967,295)32 bits / 4 bytes
u640 to 2⁶⁴-1 ( > 18×10¹⁸)64 bits / 8 bytes
u1280 to 2¹²⁸-1 ( > 34×10³⁷)128 bits / 16 bytes

Signed integers

TypeRangeSize
i8-2⁷ (-128) to 2⁷-1 (127)8 bits / 1 byte
i16-2¹⁵ (-32,768) to 2¹⁵-1 (32,767)16 bits / 2 bytes
i32-2³¹ (-2,147,483,648) to 2³¹-1 (2,147,483,647)32 bits / 4 bytes
i64-2⁶³ ( ≈ -9×10¹⁵) to 2⁶³-1 ( ≈ 9×10¹⁵)64 bits / 8 bytes
i128-2¹²⁷ ( ≈ -34×10³⁷) to 2¹²⁷-1 ( ≈ 34×10³⁷)128 bits / 16 bytes

Floating-point numbers

TypeValuesSize
f32See description32 bits / 4 bytes
f64See description64 bits / 8 bytes

Floating-point numbers are defined in IEEE 754-2008. They can mostly be considered as decimal numbers, for a deeper explanation, please refers to the Single-precision floating-point format (for f32) and Double-precision floating-point format (for f64) articles on Wikipedia.

They can store positive or negative values, but also be in one of those three states:

  • positive infinity, can be result of something like 1.0/0.0;
  • negative infinity, can be result of something like -1.0/0.0;
  • not a number, can be result of a square root of negative number (aka. complex number).

Textual data

TypeValuesSize
charAny valid Unicode scalar value32 bits / 4 bytes
stringAny valid UTF-8 textVariable

All textual information is represented as Unicode. A char uses 4 bytes to store any Unicode scalar value, as defined in Unicode Standard. Unlike many other programming languages, Mélodium does not assume a char and a byte (nor combination of bytes) to be equivalent at all, for many reasons such as:

  • a byte only have 256 values, while all human languages combined have much more "letters";
  • a letter in Unicode Text Format can be up to 4 bytes;
  • lot of values are illegal according to Unicode;
  • Unicode standard provide a strong universality of what textual data can be represented;
  • making data types reliable, each one having its own purpose, then char guarantees valid text data while byte only assume it is data.

The string data type can represent any UTF-8 text and its size depends on the length of the text. Interestingly, strings are not a combination of chars, but real UTF-8 strings. Taking the text Mélodium and putting it as vector of chars, 32 bytes (8 chars × 4 bytes) are used, but as string only 9 bytes. This technical subtility is transparent for users and conversion treatments are provided if needed.

Mélodium can handle many encodings through its encoders and decoders, taking and providing byte streams.