millfork/docs/lang/literals.md

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Literals and initializers

Numeric literals

Decimal: 1, 10

Binary: %0101, 0b101001

Quaternary: 0q2131

Octal: 0o172

Hexadecimal: $D323, 0x2a2

String literals

String literals are surrounded with double quotes and followed by the name of the encoding:

"this is a string" ascii

Characters between the quotes are interpreted literally, there are no ways to escape special characters or quotes.

In some encodings, multiple characters are mapped to the same byte value, for compatibility with multiple variants.

Currently available encodings:

• ascii – standard ASCII

• pet or petscii – PETSCII (ASCII-like character set used by Commodore machines)

• scr – Commodore screencodes

• apple2 – Apple II charset ($A0–$FE)

• bbc – BBC Micro and ZX Spectrum character set

• jis or jisx – JIS X 0201

• iso_de, iso_no, iso_se, iso_yu – various variants of ISO/IEC-646

• iso_dk, iso_fi – aliases for iso_no and iso_se respectively

When programming for Commodore, use pet for strings you're printing using standard I/O routines and scr for strings you're copying to screen memory directly.

Character literals

Character literals are surrounded by single quotes and followed by the name of the encoding:

'x' ascii

From the type system point of view, they are constants of type byte.

Array initialisers

An array is initialized with either:

• a string literal

• a file expression

• a for-style expression

• a list of byte literals and/or other array initializers, surrounded by brackets:

  array a = [1, 2] array b = "----" scr array c = ["hello world!" ascii, 13] array d = file("d.bin") array e = file("d.bin", 128, 256) array f = for x,0,until,8 [x * 3 + 5] // equivalent to [5, 8, 11, 14, 17, 20, 23, 26]

Trailing commas ([1, 2,]) are not allowed.

The parameters for file are: file path, optional start offset, optional length (start offset and length have to be either both present or both absent).

The for-style expression has a variable, a starting index, a direction, a final index, and a parametrizable array initializer. The initializer is repeated for every value of the variable in the given range.