Hi Damien,
Bigloo complies with the R5RS specification (see section 4.2) that says:
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case <key> <clause1> <clause2> ..., library syntax
Syntax: <Key> may be any expression. Each <clause> should have the form
((<datum1> ...,) <expression1> <expression2> ...,),
where each <datum> is an external representation of some object. All the
<datum>s must be distinct. The last <clause> may be an ``else clause,'' which
has the form
(else <expression1> <expression2> ...,).
Semantics: A case expression is evaluated as follows. <Key> is evaluated and
its result is compared against each <datum>. If the result of evaluating <key>
is equivalent (in the sense of eqv?; see section Equivalence predicates) to a
<datum>, then the expressions in the corresponding <clause> are evaluated from
left to right and the result(s) of the last expression in the <clause> is(are)
returned as the result(s) of the case expression. If the result of evaluating
<key> is different from every <datum>, then if there is an else clause its
expressions are evaluated and the result(s) of the last is(are) the result(s)
of the case expression; otherwise the result of the case expression is
unspecified.
(case (* 2 3)
((2 3 5 7) 'prime)
((1 4 6 8 9) 'composite)) => composite
(case (car '(c d))
((a) 'a)
((b) 'b)) => unspecified
(case (car '(c d))
((a e i o u) 'vowel)
((w y) 'semivowel)
(else 'consonant)) => consonant
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You can observe that with:
(pp (expand '(case x (("foo") 1) (("bar" ) 2))))
=>
(let ((case-value x))
(if (eqv? case-value '"foo")
1
(if (eqv? case-value '"bar") 2 #unspecified)))
Cheers,
--
Manuel
