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31 lines
1.3 KiB
Markdown
31 lines
1.3 KiB
Markdown
# Case-Lambda Library
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The `(scheme case-lambda)` library exports the `case-lambda` syntax.
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For more information see the [R<sup>7</sup>RS Scheme Specification](../../r7rs.pdf).
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- [`case-lambda`](#case-lambda)
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# case-lambda
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*Syntax*
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(case-lambda {clause} ...)
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Syntax: Each `{clause}` is of the form `({formals} {body})`, where `{formals}` and `{body}` have the same syntax as in a lambda expression.
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Semantics: A `case-lambda` expression evaluates to a procedure that accepts a variable number of arguments and is lexically scoped in the same manner as a procedure resulting from a lambda expression.
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When the procedure is called, the first `{clause}` for which the arguments agree with `{formals}` is selected, where agreement is specified as for the `{formals}` of a lambda expression. The variables of `{formals}` are bound to fresh locations, the values of the arguments are stored in those locations, the `{body}` is evaluated in the extended environment, and the results of `{body}` are returned as the results of the procedure call.
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It is an error for the arguments not to agree with the `{formals}` of any `{clause}`.
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(define range
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(case-lambda
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((e) (range 0 e))
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((b e) (do ((r '() (cons e r))
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(e (- e 1) (- e 1)))
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((< e b) r)))))
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(range 3) => (0 1 2)
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(range 3 5) => (3 4)
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