symbol -- r7rs Type

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Super-types

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• (none);

Referent definitions as input

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• symbol?;
• symbol=?;
• symbol->string;

Referent definitions as output

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• string->symbol;

Predicate

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symbol?

Description

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Symbols are objects whose usefulness rests on the fact that two symbols are identical (in the sense of eqv?) if and only if their names are spelled the same way. For instance, they can be used the way enumerated values are used in other languages.

The rules for writing a symbol are exactly the same as the rules for writing an identifier; see sections on identifiers and symbols.

It is guaranteed that any symbol that has been returned as part of a literal expression, or read using the read procedure, and subsequently written out using the write procedure, will read back in as the identical symbol (in the sense of eqv?).

Note: Some implementations have values known as uninterned symbols, which defeat write/read invariance, and also violate the rule that two symbols are the same if and only if their names are spelled the same. This report does not specify the behavior of implementation-dependent extensions.

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The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.

Categories

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• types-disjoint;

Categories recursive

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• types;