Decimal integer constants consist an optional negative sign, a nonzero digit, and optionally more decimal digits, the first not being zero. In regular expression terms:
-?[1-9][0-9]*
Examples:
1
12
-12
Octal constants begin with a zero digit:
0 # Zero. Technically octal not decimal, not that it matters.
010 # Decimal eight.
0100 # Decimal sixty-four.
Hex constants begin with a 0x. Alphabetic digits may be upper or lower case:
0xa # Decimal ten.
0xA # Decimal ten.
0x10 # Decimal sixteen.
0x100 # Decimal two hundred fifty six.
Unsigned decimal constants are written with a 0u prefix:
0u1 # Unsigned one.
0u10 # Unsigned ten.
0u100 # Unsigned one hundred.
Unsigned hexadecimal constants are written with a 0ux prefix:
0ux1 # Unsigned one. 0ux10 # Unsigned sixteen. 0ux100 # Unsigned two hundred fifty six.
The compiler uses type inference to determine the type of an integer constant. This is done in src/lib/compiler/front/typer/types/resolve-overloaded-literals.pkg.
Signed integers may be assigned to any of the types:
tagged_int::Int # The default, and the most common.
one_word_int::Int # 32-bit integer.
two_word_int::Int # 64-bit integer.
multiword_int::Int # Indefinite precision.
If type inference does not yield a type for the constant it defaults to tagged_int::Int.
Unsigned integers may be assigned to any of the types:
tagged_unt::Unt # The default, and the most common.
one_byte_unt::Unt # 8-bit unsigned integer.
one_word_unt::Unt # 32-bit unsigned integer.
two_word_unt::Unt # 64-bit unsigned integer.
If type inference does not yield a type for the constant it defaults to tagged_unt::Unt.