2018-04-02 22:21:26 +00:00
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[< back to index](../index.md)
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2018-01-04 00:15:04 +00:00
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# Literals and initializers
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2018-02-27 12:26:56 +00:00
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## Numeric literals
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Decimal: `1`, `10`
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Binary: `%0101`, `0b101001`
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2018-03-03 00:21:57 +00:00
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Quaternary: `0q2131`
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Octal: `0o172`
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Hexadecimal: `$D323`, `0x2a2`
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## String literals
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2018-07-06 22:58:44 +00:00
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String literals are surrounded with double quotes and optionally followed by the name of the encoding:
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"this is a string" ascii
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"this is also a string"
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Characters between the quotes are interpreted literally,
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there are no ways to escape special characters or quotes.
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2018-04-02 17:47:11 +00:00
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In some encodings, multiple characters are mapped to the same byte value,
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for compatibility with multiple variants.
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Currently available encodings:
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* `default` – default console encoding (can be omitted)
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* `scr` – default screencodes
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(usually the same as `default`, a notable exception are the Commodore computers)
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* `ascii` – standard ASCII
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* `pet` or `petscii` – PETSCII (ASCII-like character set used by Commodore machines)
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* `cbmscr` or `petscr` – Commodore screencodes
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* `apple2` – Apple II charset ($A0–$FE)
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* `bbc` – BBC Micro and ZX Spectrum character set
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2018-04-02 19:06:18 +00:00
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* `jis` or `jisx` – JIS X 0201
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* `iso_de`, `iso_no`, `iso_se`, `iso_yu` – various variants of ISO/IEC-646
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* `iso_dk`, `iso_fi` – aliases for `iso_no` and `iso_se` respectively
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2018-02-27 12:26:56 +00:00
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When programming for Commodore,
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use `pet` for strings you're printing using standard I/O routines
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and `petscr` for strings you're copying to screen memory directly.
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If the characters in the literal cannot be encoded in particular encoding, an error is raised.
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However, if the command-line option `-flenient-encoding` is used,
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then literals using `default` and `scr` encodings replace unsupported characters with supported ones
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and a warning is issued.
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For example, if `-flenient-encoding` is enabled, then a literal `"£¥↑ž©ß"` is equivalent to:
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* `"£Y↑z(C)ss"` if the default encoding is `pet`
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* `"£Y↑z©ss"` if the default encoding is `bbc`
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* `"?Y^z(C)ss"` if the default encoding is `ascii`
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* `"?Y^ž(C)ss"` if the default encoding is `iso_yu`
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* `"?Y^z(C)ß"` if the default encoding is `iso_de`
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* `"?¥^z(C)ss"` if the default encoding is `jisx`
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Note that the final length of the string may vary.
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2018-04-02 19:06:18 +00:00
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## Character literals
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2018-07-06 22:58:44 +00:00
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Character literals are surrounded by single quotes and optionally followed by the name of the encoding:
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'x' ascii
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'W'
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From the type system point of view, they are constants of type byte.
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2018-07-06 22:58:44 +00:00
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If the characters in the literal cannot be encoded in particular encoding, an error is raised.
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However, if the command-line option `-flenient-encoding` is used,
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then literals using `default` and `scr` encodings replace unsupported characters with supported ones.
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If the replacement is one characacter long, only a warning is issued, otherwise an error is raised.
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2018-02-27 12:26:56 +00:00
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## Array initialisers
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2018-04-02 22:21:26 +00:00
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An array is initialized with either:
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* a string literal
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* a `file` expression
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* a `for`-style expression
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2018-06-18 00:52:14 +00:00
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* a format, followed by an array initializer:
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* `@word` (=`@word_le`): for every term of the array initializer, emit two bytes, first being the low byte of the value, second being the high byte:
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`@word [$1122]` is equivalent to `[$22, $11]`
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* `@word_be` – like the above, but opposite:
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`@word_be [$1122]` is equivalent to `[$11, $22]`
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2018-04-02 22:21:26 +00:00
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* a list of byte literals and/or other array initializers, surrounded by brackets:
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array a = [1, 2]
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array b = "----" scr
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array c = ["hello world!" ascii, 13]
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array d = file("d.bin")
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array e = file("d.bin", 128, 256)
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array f = for x,0,until,8 [x * 3 + 5] // equivalent to [5, 8, 11, 14, 17, 20, 23, 26]
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Trailing commas (`[1, 2,]`) are not allowed.
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The parameters for `file` are: file path, optional start offset, optional length
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(start offset and length have to be either both present or both absent).
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2018-04-02 22:21:26 +00:00
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The `for`-style expression has a variable, a starting index, a direction, a final index,
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and a parameterizable array initializer.
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The initializer is repeated for every value of the variable in the given range.
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