/usr/lib/help/and-letstar is in scheme9 2013.11.26-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | S9 LIB (and-let* <binding> ... <body>) ==> object
(load-from-library "and-letstar.scm")
Each <binding> has the form (<variable> <expression>) and binds
the given <variable> to the normal form of <expression>.
Like LET*, AND-LET* evaluates its <binding>s in sequence, so each
<expression> is evaluated in an environment that includes all previous
<binding>s of the same AND-LET*. Unlike LET*, though, AND-LET* returns
#F immediately as soon as one of its <expression>s evaluates to #F.
Only when all <expression>s evaluate to non-#F values, it evaluates
<body> and returns its value. AND-LET* expands as follows:
(and-let* ((<var1> <expr1>) ---> (let ((<var1> <expr1>))
... (and <var1>
(<varN> <exprN>)) ...
<body>) (let ((<varN> <exprN>))
(and <varN>
<body>))))
This is only a subset of SRFI-2 AND-LET*.
(and-let* ((a '((x . 1)))
(a (assq 'x a)))
(cdr a)) ==> 1
(and-let* ((a '((x . 1)))
(a (assq 'z a)))
(cdr a)) ==> #f
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