2019-03-18 17:20:42 +01:00
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# Working With Characters
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RETRO provides words for working with ASCII characters.
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## Prefix
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Character constants are returned using the `$` prefix.
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2019-03-19 16:12:16 +01:00
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## Namespace
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Words operating on characters are in the `c:` namespace.
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## Classification
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RETRO provides a number of words to determine if a character
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fits into predefined groups.
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The primary words for this are:
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* `c:consonant?`
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* `c:digit?`
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* `c:letter?`
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* `c:lowercase?`
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* `c:uppercase?`
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* `c:visible?`
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* `c:vowel?`
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* `c:whitespace?`
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There are also corresponding "not" forms:
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* `c:-consonant?`
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* `c:-digit?`
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* `c:-lowercase?`
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* `c:-uppercase?`
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* `c:-visible?`
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* `c:-vowel?`
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* `c:-whitespace?`
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All of these take a character and return either a `TRUE` or
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`FALSE` flag.
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## Conversions
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A few words are provided to convert case. Each takes a character
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and returns the modified character.
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* `c:to-lower`
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* `c:to-number`
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* `c:to-upper`
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* `c:toggle-case`
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RETRO also has `c:to-string`, which takes a character and
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creates a new temporary string with the character.
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## I/O
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Characters can be displayed using `c:put`.
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```
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$a c:put
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```
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With the default system on BSD, Linux, and macOS (and other
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Unix style hosts), `c:get` is provided to read input. This
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may be buffered, depending on the host.
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