Literals

Literals are fixed values written directly in source code – such as numbers, strings, or booleans.

Bool

• True, False are Bool,
  • uppercase as they are constants (as in Python).

Integer

• 123 is an integer literal of arbitrary precision
  • Typical integer literals like 123456 are interpreted as Int
    • in case of type inferring, parameter overloading and template matching.
  • Big integer literals are interpreted as Int64, Int128, Int256, BigInt, if required due to the size.
  • Positive integer literals up to a certain size can implicitly be used as Int8/16/32/64/128/256 (i.e. signed), as there is no loss of information.
    • Up to 127 -> Int8
    • Up to 32'767 -> Int16
    • Up to 2'147'483'647 -> Int32
    • Up to 9'223'372'036'854'775'807 -> Int64/Int
    • Up to 170'141'183'460'469'231'731'687'303'715'884'105'727 -> Int128
    • Up to 57'896'044'618'658'097'711'785'492'504'343'953'926'634'992'332'820'282'019'728'792'003'956'564'819'967 -> Int256
  • Negative integer literals down to a certain size can implicitly be used as Int8/16/32/64/128/256, as there is no loss of information.
    • Down to -128 -> Int8
    • Down to -32'768 -> Int16
    • Down to -2'147'483'648 -> Int32
    • Down to -9'223'372'036'854'775'808 -> Int64/Int
    • Down to -170'141'183'460'469'231'731'687'303'715'884'105'728 -> Int128
    • Down to -57'896'044'618'658'097'711'785'492'504'343'953'926'634'992'332'820'282'019'728'792'003'956'564'819'968 -> Int256
  • Positive integer literals up to a certain size can implicitly be used as UInt8/16/32/64/128/256, as there is no loss of information.
    • Up to 255 -> UInt8
    • Up to 65'535 -> UInt16
    • Up to 4'294'967'295 -> UInt32
    • Up to 18'446'744'073'709'551'615 -> UInt64/UInt
    • Up to 340'282'366'920'938'463'463'374'607'431'768'211'455 -> UInt128
    • Up to 115'792'089'237'316'195'423'570'985'008'687'907'853'269'984'665'640'564'039'457'584'007'913'129'639'935 -> UInt256
  • Examples:
    • Int8 a = 1 // Works because 1 fits into Int8
    • Int8 b = 127 // Works because 127 fits into Int8
    • Int8 c = 128 // Error because 128 does not fit into Int8
    • Int8 d = -128 // Works because -128 fits into Int8
    • Int8 e = -129 // Error because -129 does not fit into Int8
    • UInt8 f = 255 // Works because 255 fits into UInt8
    • UInt8 g = 256 // Error because 256 does not fit into UInt8
    • UInt8 h = -1 // Error because -1 does not fit into UInt8
    • Int16 i = 32767 // Works
    • Int32 j = 2'147'483'647 // Works
    • Int64 k = 9'223'372'036'854'775'807 // Works
    • Int l = a // Works because Int8 fits into Int32
    • UInt m = l // Error because Int does not always fit into UInt
      • UInt m = UInt(l) // Works
    • Int n = m // Error because UInt does not always fit into Int
      • Int n = Int(m) // Works
  • Integer literals can automatically be converted to other sizes than Int64,
    • according to the C++ rules (admittedly without knowing the details),
    • but only if the converted-to-type can contain the value of the literal.
  • Difficult: Constexpr constructor that accepts an arbitrary precision integer literal and can store that in ROM
    • Store as array of Int/UInt
  • Suffixes/postfixes to write integer literals of a certain size:
    • 123u is UInt
      • -123u is an error.
    • 123i8, 123i16, 123i32, 123i64,
    • 123u8, 123u16, 123u32, 123u64 (as in Rust)
  • -123 is always Int (signed)
• Hexadecimal, octal, and binary literals are UInt (i.e. unsigned)
  • Unsigned, as usually you want to describe flags, bit masks, hardware registers, hardware addresses, or color values, where signed integer doesn’t fit.
    • As unsigned integer literals up to a certain size can implicitly be converted to Int (i.e. signed), usually it is possible to give a hex literal as an Int argument
      • Up to 0x7f -> Int8
      • Up to 0x7fff -> Int16
      • Up to 0x7fffffff -> Int32
      • Up to 0x7fffffffffffffff -> Int64/Int
    • Otherwise you have to cast it like Int mostNegativeInt = Int(0x8000000000000000).
  • 0xffffffff is UInt in hexadecimal
  • 0b1011 is UInt in binary
  • 0o123 is UInt in octal
    • Using 0o as in Python,
    • not 0123, as that IMHO is confusing/unexpected, even though it is C++ standard.
• Int vs. Bool
  • Int a = True // Error,
    • because Bool is not an Int
    • because a Bool should not be accidentally interpreted as an Int
    • cast if necessary: Int a = Int(True)
  • Bool a = 1 // Error,
    • because Int is not a Bool
    • because an Int should not be accidentally interpreted as a Bool
    • cast if necessary: Bool a = Bool(1)

Floating Point

• 1.0 is a floating point literal
  • Floating point literals are interpreted according to the size/precision requirements.
    • Counting the decimal places
      (including the digits before the decimal point, the significant digits after the decimal point and the trailing zeros!),
      then the rules are:
      • up to 15 decimal places -> Float64 (AKA Float)
      • up to 34 decimal places -> Float128
      • up to 71 decimal places -> Float256
      • more decimal places -> BigFloat
        • Difficult: Constexpr constructor that accepts an arbitrary precision float literal and can store that in ROM
          • Store the mantissa as arbitrary precision integer (i.e. array of Int), plus the exponent as arbitrary precision integer (i.e. array of Int, most always only a single Int)
    • So a plain float literal like 1.0 is a Float (AKA Float64). This way the precision is the same as in C++, but there 1.0 is called a double while 1.0f is called a (single) float.
  • Can implicitly be converted to any smaller float type into which it still fits exactly,
    • otherwise explicit cast necessary: Float16(3.1415926)
    • Note: 0.1 as Float64 has the significand 1001100110011001100110011001100110011001100110011010, so this can not implicitly be converted to Float32 or Float16.
  • Postfixes to write float literals with a certain precision:
    0.1f16, 0.1f32, 0.1f64, 0.1f128, 0.1f256 (as in Rust)
    • That probably is clearer than 0.1h, 0.1s, 0.1d, 0.1q, 0.1o for half, single, double, quadruple, octuple precision.
    • Use of 0.1f for Float AKA Float64 would be confusing, as in C++ 0.1f means single float AKA Float32.
  • To ensure the literal has Float128/Float256/BigFloat precision you may add trailing zeros (0.1000000000000000…).
• Infinity/-Infinity is a Float literal for infinity values,
  • that can be converted to any float type.
• NaN is a Float literal for NaN (“not a number”) values,
  • that can be converted to any float type.

String

• "Text" is a StringView with UTF-8 encoding.
  • No null termination.
    • If necessary
      • use "Text"sz, "Text\0" or
      • convert using StringZ("Text").
  • Data is typically stored in read-only data segments (“.rodata”) or ROM.
  • A Cilia-to-C++-transpiler would translate every string literal to a C++ string_view-literal:
    • "Text" -> u8"Text"sv
    • ("Text"sv as to avoid null termination, and u8"Text" as to have UTF-8 encoding.)
  • A StringView starts like a String does: pointer to first character plus length,
    • so slicing of String to StringView is possible.
    • TODO This would probably not work with small string optimization (SSO), so it is of limited use.
• Multiline String Literal
  • Use triple double-quotes """ to start and end the literal.

  • """
    First line
    Second line
    """
    

  • Similar to Swift, Julia, Java 15, C# 11, …
  • Also as single line string literal with very few restrictions, good for RegEx
    • """(.* )whatever(.*)"""
  • Opening Delimiter Rules
    • If the opening """ is followed by a newline, that newline is not part of the string content.
    • This allows the content to start cleanly on the next line.
  • Closing Delimiter & Indentation (Strip-Logic)
    • The position of the closing """ defines the indentation guide.
    • If the closing """ is on its own line:
      • The newline preceding it is removed from the content.
      • The exact sequence of whitespace (spaces/tabs) before the closing """ is treated as a “prefix” and is stripped from every line of the string.
    • Indentation Safety: It is a compile-time error if any non-empty line begins with less indentation than the closing delimiter.
  • Whitespace & Line Handling
    • Trailing Whitespace: Whitespace at the end of lines is preserved.
    • Blank Lines: Lines containing only whitespace that is shorter than the indentation guide are treated as empty lines (\n).
  • To include """ within the string content, the literal can be opened and closed with more than three double-quotes (e.g., """").
    • The closing delimiter must match the number of quotes used for the opening delimiter.
    • This eliminates the need for escape backslashes within the literal, ensuring truly “raw” content.
• Interpolated Strings
  • f"M[{i},{j}] = {M[i, j]}"
    • like f-strings in Python.
  • Curly braces ({}) are used in std::format already.
  • f"..." as in format.
  • TODO Any reason to use/prefer any other syntax?
    • Maybe $"M[{i},{j}] = {M[i, j]}" like in C#?
• Alternative string literals
  • Prefixes
    • as in C++:
      • u"..." and u'...' for UTF-16
      • U"..." and U'...' for UTF-32
    • No u8"..." and no u8'...' for UTF-8, as that is the default in Cilia.
    • Maybe a"..." for ASCII and l"..." for Latin-1.
  • User defined string suffixes
    • as in C++:
      • "..."s for std::string.
    • No "..."sv for std::string_view, as that is the default in Cilia.
    • "..."sz for null terminated strings.
      • Type of "..."sz is Char*.
      • "...\0" is a StringView of a zero terminated string.
  • All these available for multiline string literals and interpolated strings, too.
    • TODO Any reason, not to?

Char

• ' ' is a character literal.
  • 'A' is an ASCII character literal, a Char8. (Can implicitly be converted to Char16 and Char32.)
  • 'Ä' is a non-ASCII Latin-1 character literal, a Char8. (Can implicitly be converted to Char16 and Char32.)
  • 'Ω' is a Char16 character literal. (Can implicitly be converted to Char32.)
  • '𝄞' is a Char32 character literal.
  • '👮🏻' is an invalid character literal, as it is a grapheme cluster consisting of multiple code points. Use the string literal "👮🏻" instead.

Array

• [1, 2, 3] is an array (here an Int[3]),
  • all elements have the same type.
• {1, "Text", 3.0} is an initialization list,
  • e.g. for Tuple or Pair.
• [ 1: "one", 2: "two", 3: "three", 4: "four" ] is a String[Int] (AKA Map<Int, String>).

• String[Int] keywords = [
      1: "one"
      2: "two"
      3: "three"
      4: "four"
  ]
  

• ContactInfo[String] contactInfoForID = [
      "John Doe": {"John", "Doe", "03465 452634"}
      "Jane Doe": {"Jane", "Doe", "03245 687534"}
  ]
  

Misc

• NullPtr is the null pointer,
  • it is of the type NullPtrType,
  • explicit cast necessary to convert any pointer to Int.
• User Defined Literals
  • The same rules as in C++.