/usr/lib/s9fes/help/and-letstar is in scheme9 2010.11.13-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | 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 <bindings>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.
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
|