by Joo ChurlSoo
This copy of the SRFI 86 specification document is distributed as part of the Racket package srfi-doc.
The canonical source of this document is https://srfi.schemers.org/srfi-86/srfi-86.html.
This SRFI is currently in final status. Here is an explanation of each status that a SRFI can hold. To provide input on this SRFI, please send email to srfi-86@nospamsrfi.schemers.org. To subscribe to the list, follow these instructions. You can access previous messages via the mailing list archive.
Unlike the values/call-with-values mechanism of
R5RS, this SRFI uses an explicit representation for multiple return
values as a single value, namely a procedure. Decomposition of
multiple values is done by simple application. Each of the two
macros, mu and nu, evaluates to a procedure
that takes one procedure argument. The mu and
nu can be compared with lambda. While
lambda expression that consists of <formals> and <body>
requires some actual arguments later when the evaluated
lambda expression is called, mu and
nu expressions that consist of <expression>s
corresponding to actual arguments of lambda require
<formals> and <body>, that is, an evaluated lambda
expression, later when the evaluated mu and
nu expressions are called.
This SRFI also introduces new let-syntax depending on
mu and nu to manipulate multiple values,
alet and alet* that are compatible with
let and let* of R5RS in single value
bindings. They also have a binding form making use of
values and call-with-values to handle
multiple values. In addition, they have several new binding forms for
useful functions such as escape, recursion, etc.
It is impossible to bind the evaluated result of values
expression to a single variable unlike other Scheme expressions.
Moreover, the pair of values and
call-with-values is clumsy to use and somewhat slow under
some circumstances. A solution would be to enclose the arguments of
values expression in a procedure of one argument, a
consumer procedure of call-with-values. The following are examples to
show the differences.
(define v (values 1 2 3)) => error (define v (lambda () (values 1 2 3))) => (lambda () (values 1 2 3)) (define m (mu 1 2 3)) => (lambda (f) (f 1 2 3)) (define a (apply values 1 '(2 3))) => error (define a (lambda () (apply values 1 '(2 3)))) => (lambda () (apply values 1 '(2 3))) (define n (nu 1 '(2 3))) => (lambda (f) (apply f 1 '(2 3))) (call-with-values v list) => (1 2 3) (m list) => (1 2 3) (call-with-values a list) => (1 2 3) (n list) => (1 2 3)
The alet and alet* are cases in point to use
mu and nu. The differences between this
let-syntax and others, and some additional functions are
best explained by simple examples.
The following are rest argument forms of each SRFI.
In SRFI 11:
(let-values ((a (values 1 2)) ((b c) (values 3 4))) (list a b c)) => ((1 2) 3 4)
In SRFI 71:
(srfi-let (((values . a) (values 1 2)) ((values b c) (values 3 4))) (list a b c)) => ((1 2) 3 4)
In this SRFI:
(alet (a (mu 1 2) ((b c) (mu 3 4))) (list a b c)) => ((1 2) 3 4)
The expressions for alet bindings are evaluated in
sequence from left to right unlike let of R5RS and
let of SRFI 71.
In SRFI 71:
(srfi-let ((a (begin (display "1st") 1)) (b c (values (begin (display "2nd") 2) 3)) (d (begin (display "3rd") 4)) ((values e . f) (values (begin (display "4th") 5) 6))) (list a b c d e f)) => 2nd4th1st3rd(1 2 3 4 5 (6))
In this SRFI:
(alet ((a (begin (display "1st") 1))
(b c (mu (begin (display "2nd") 2) 3))
(d (begin (display "3rd") 4))
((e . f) (mu (begin (display "4th") 5) 6)))
(list a b c d e f))
=> 1st2nd3rd4th(1 2 3 4 5 (6))
The bindings that require multiple values can take multiple expressions, if syntactically possible, as well as a single expression that produce multiple values.
(alet* (((a b) (mu 1 2)) ((c d e) a (+ a b c) (+ a b c d)) ((f . g) (mu 5 6 7)) ((h i j . k) e 9 10 h i j)) (list a b c d e f g h i j k)) => (1 2 1 4 8 5 (6 7) 8 9 10 (8 9 10))
The named-alet and named-alet* are
allowed to take multiple values bindings.
In SRFI 71:
(srfi-let tag ((a 1) (b 2) (c 3) (d 4) (e 5)) (if (< a 10) (tag 10 b c d e) (list a b c d e))) => (10 2 3 4 5)
In this SRFI:
(alet* tag ((a 1) (a b b c (mu (+ a 2) 4 5 6)) ((d e e) b 5 (+ a b c)))
(if (< a 10) (tag a 10 b c c d e d) (list a b c d e)))
=> (10 6 6 5 5)
They have a new binding form that has a recursive function like
named-alet. It is also allowed to take multiple values
bindings.
(alet* ((a 1)
((b 2) (b c c (mu 3 4 5)) ((d e d (mu a b c)) . intag) . tag)
(f 6))
(if (< d 10)
(intag d e 10)
(if (< c 10)
(tag b 11 c 12 a b d intag)
(list a b c d e f))))
=> (1 11 12 10 3 6)
They have a new binding form that has an escape function.
(alet ((exit)
(a (begin (display "1st") 1))
(b c (mu (begin (display "2nd") 2) (begin (display "3rd") 3))))
(display (list a b c))
(exit 10)
(display "end"))
=> 1st2nd3rd(1 2 3)10
The and-let and and-let* are
integrated into the alet and alet* with a
syntactic keyword and.
(alet ((and (a (begin (display "1st") 1)) (b (begin (display "2nd") 2)) (c (begin (display "false") #f)) (d (begin (display "3nd") 3)))) (list a b c d)) => 1st2ndfalse#f (alet ((and (a (begin (display "1st") 1)) (b (begin (display "2nd") 2) (< b 2)) ; different from SRFI 2 (c (begin (display "false") #f)) (d (begin (display "3nd") 3)))) (list a b c d)) => 1st2nd#f
The rest-values of SRFI 51 is integrated into the
alet and alet* with
syntactic keywords opt and cat in the
similar way to let-optionals in Scsh.
((lambda (str . rest)
(alet* ((len (string-length str))
(opt rest
(start 0 (integer? start)
(if (< start 0) 0 (if (< len start) len start))) ;true
(end len (integer? end)
(if (< end start) start (if (< len end) len end)))));true
(substring str start end))) "abcdefg" 1 20)
=> "bcdefg"
((lambda (str . rest)
(alet* ((len (string-length str))
(min (apply min rest))
(cat rest
(start 0 (= start min)
(if (< start 0) 0 (if (< len start) len start))) ;true
(end len (integer? end)
(if (< end start) start (if (< len end) len end)))));true
(substring str start end))) "abcdefg" 20 1)
=> "bcdefg"
((lambda (str . rest)
(alet ((cat rest
(start 0
(and (list? start) (= 2 (length start))
(eq? 'start (car start)))
(cadr start)) ; true
(end (string-length str)
(and (list? end) (= 2 (length end)) (eq? 'end (car end)))
(cadr end)))) ; true
(substring str start end))) "abcdefg" '(end 6) '(start 1))
=> "bcdef"
The let-keywords and let-keywords*
are integrated into the alet and
alet* with a syntactic keyword key.
They use any Scheme objects as keywords.
(define rest-list '(a 10 cc 30 40 b 20))
(alet ((key rest-list (a 1) (b 2) ((c 'cc) 3) . d)) (list a b c d))
=> (10 2 30 (40 b 20))
(alet ((key rest-list (a 1) (b 2) ((c 'cc) 3) #f . d)) (list a b c d))
=> (10 2 30 (40 b 20))
(alet ((key rest-list (a 1) (b 2) ((c 'cc) 3) #t . d)) (list a b c d))
=> (10 20 30 (40))
(define rest (list 'a 10 'd 40 "c" 30 50 'b 20))
(alet ((key rest (a 1) (b 2) ((c "c") 3) . d)) (list a b c d))
=> (10 2 30 (d 40 50 b 20))
(alet ((key rest (a 1) (b 2) ((c "c") 3) #f . d)) (list a b c d))
=> (10 2 3 (d 40 "c" 30 50 b 20))
(alet ((key rest (a 1) (b 2) ((c "c") 3) #t . d)) (list a b c d))
=> (10 20 30 (d 40 50))
((lambda (m . n)
(alet* ((opt n (a 10) (b 20) (c 30) . d)
(key d (x 100) (y 200) (a 300)))
(list m a b c x y)))
0 1 2 3 'a 30 'y 20 'x 10)
=> (0 30 2 3 10 20)
((lambda (m . n)
(alet* ((key n (x 100) (y 200) (a 300) . d)
(opt d (a 10) (b 20) (c 30)))
(list m a b c x y)))
0 'a 30 'y 20 'x 10 1 2 3)
=> (0 1 2 3 10 20)
The letrecand letrec* are integrated
into the alet and alet* with a
syntactic keyword rec.
(alet* ((a 1) (rec (a 2) (b 3) (b (lambda () c)) (c a)) (d 50)) (list a (b) c d)) => '(2 2 2 50)
They have a binding form that use call-with-values
and values to handle multiple values with a syntactic
keyword values like SRFI 71.
(alet ((a b (mu 1 2))
(values c d (values 3 4)) ;This is different from SRFI 71.
((e f) (mu 5 6))
((values g h) (values 7 8))
((i j . k) (nu 9 '(10 11 12)))
((values l m . n) (apply values 13 '(14 15 16)))
o (mu 17 18)
((values . p) (values 19 20)))
(list a b c d e f g h i j k l m n o p))
=> (1 2 3 4 5 6 7 8 9 10 (11 12) 13 14 (15 16) (17 18) (19 20))
They have a new binding form that works as an intervening external
environment in alet and as an intervening internal
environment in alet*.
(alet ((a 1)
(() (define a 10) (define b 100))
(b a))
(list a b))
=> (1 10)
(alet* ((a 1)
(() (define a 10) (define b 100))
(b a))
(list a b))
=> (10 10)
(mu <expr> ...) => (lambda (f) (f <expr> ...)) (nu <expr> ... <exprn>) => (lambda (f) (apply f <expr> ... <exprn>))
The <exprn> should be a list.
Each macro evaluates to a procedure of one argument. The environment
in effect when the macro expression was evaluated is remembered as
part of the procedure. When the procedure is later called with an
actual argument, a procedure, the environment in which the macro was
evaluated is extended by binding <expr>s to the corresponding
variables in the formal argument list of the argument procedure. The
argument procedure of mu is called with the <expr>s,
and that of nu is applied to APPLY procedure with the
<expr>s.
(alet (<binding spec> ...) body ...) (alet* (<binding spec> ...) body ...)
syntax-rules identifier: opt
cat key and
rec values
<binding spec>:
(<var> <expr>)
(<var1> <var2> <var3> ... <expr>)
((<var>) <expr>)
((<var1> <var2> <var3> ... ) <expr>)
((<var1> ... <varm> . <varn>) <expr>)
((<var1> <var2> <var3> ... ) <expr1> <expr2> <expr3> ...)
((<var1> ... <varm> . <varn>) <expr1> ... <exprm> <exprn> ...)
<var> <expr>
(<var>)
(<binding spec1> <binding spec2> ... . <var>)
(() . <var>)
(and (<var1> <expr1> [<test1>]) (<var2> <expr2> [<test2>]) ...)
(opt <rest list>
(<var1> <default1> [<test1> [<true substitute1> [<false substitute1>]]])
...
(<varn> <defaultn> [<testn> [<true substituten> [<false substituten>]]])
. [<rest var>])
(cat <rest list>
(<var1> <default1> [<test1> [<true substitute1> [<false substitute1>]]])
...
(<varn> <defaultn> [<testn> [<true substituten> [<false substituten>]]])
. [<rest var>])(key <rest list> (<var spec1> <default1> [<test1> [<true substitute1> [<false substitute1>]]]) ... (<var specn> <defaultn> [<testn> [<true substituten> [<false substituten>]]]) [<option>] . [<rest var>])
(rec (<var1> <expr1>) (<var2> <expr2>) ...)
(values <var1> <var2> ... <expr>)
((values <var1> <var2> ...) <expr>)
((values <var1> ... . <varn>) <expr>)
((values <var1> <var2> <var3> ...) <expr1> <expr2> <expr3> ...)
((values <var1> ... . <varn>) <expr1> ... <exprn> ...)
(() <expr1> <expr2> ...)
The alet* is to the alet what the
let* is to the let. However, the <binding
spec>s of alet are evaluated in sequence from left to
spec>right unlike let of
R5RS. The alet and alet* make use of
mu or nu instead of values to
handle multiple values. So, the single <expr> of multiple values
binding should be a mu or nu expression, or
its equivalent. And the number of arguments of mu or the
number of `applied' arguments of nu must match the number
of values expected by the binding specification. Otherwise an error
is signaled, as lambda expression would.
(<var> <expr>)This is the same as
let (R5RS, 4.2.2).
(<var1> <var2> <var3> ... <expr>)This is the same as 4.
((<var>) <expr>)This is the same as 1.
((<var1> <var2> <var3> ... ) <expr>)
((<var1> ... <varm> . <varn>) <expr>)The <expr> must be a
mu or nu
expression or its equivalent. The matching of <var>s to the
values of <expr> is as for the matching of <formals> to
arguments in a lambda expression (R5RS, 4.1.4).
((<var1> <var2> <var3> ... ) <expr1> <expr2> <expr3> ...)This is the same as
(let[*] ((<var1> <expr1>) (<var2> <expr2>) (<var3> <expr3>) ...).
((<var1> ... <varm> . <varn>) <expr1> ... <exprm> <exprn> ...)This is the same as
(let[*] ((<var1> <expr1>) ... (<varm> <exprm>) (<varn> (list <exprn> ...))).
<var> <expr>The <var> is a rest argument, so the <expr> should be a form that can deliver multiple values, that is, a
mu or nu expression or its equivalent.
(<var>)The <var> becomes an escape procedure that can take return values of
alet[*] as its arguments.
(<binding spec1> <binding spec2> ... . <var>)The <var> becomes a recursive procedure that takes all <vars> of <binding spec>s as arguments.
(() . <var>)The <var> becomes a recursive thunk that takes no argument.
(and (<var1> <expr1> [<test1>]) (<var2> <expr2> [<test2>]) ...)Each <expr> is evaluated sequentially and bound to the corresponding <var>. During the process, if there is no <test> and the value of <expr> is false, it stops and returns
#f. When there is a <test>, the process is continued
regardless of the value of <expr> unless the value of <test> is
false. If the value of <test> is false, it stops and returns #f.
(opt <rest list>
(<var1> <default1> [<test1> [<true substitute1> [<false substitute1>]]])
...
(<varn> <defaultn> [<testn> [<true substituten> [<false substituten>]]])
. [<rest var>])
This binds each <var> to a corresponding element of <rest list>.
If there is no more element, then the corresponding <default> is
evaluated and bound to the <var>. An error is signaled when
there are more elements than <var>s. But if <rest var> is
given, it is bound to the remaining elements. If there is a
<test>, it is evaluated only when <var> is bound to an
element of <rest list>. If it returns a false value and there is no
<false substitute>, an error is signaled. If it returns a false value
and there is a <false
substitute>, <var> is rebound to the result of evaluating <false substitute>
instead of signaling an error. If it returns a true value and there is a
<true substitute>, <var> is rebound to the result of evaluating <true
substitute>.
(cat <rest list>
(<var1> <default1> [<test1> [<true substitute1> [<false substitute1>]]])
...
(<varn> <defaultn> [<testn> [<true substituten> [<false substituten>]]])
. [<rest var>])
This is the same as the above opt except the binding
method. It temporarily binds <var> to each elements of <rest
list> sequentally, until <test> returns a true value, then
the <var> is finally bound to the passed element. If there is
no <test>, the first element of the remained <rest list>
is regarded as passing. If any element of the <rest list> does
not pass the <test>, the <default> is bound to the
<var> instead of signaling an error. If there is a <false
substitute> and <test> returns a false value, <var> is
finally bound to the result of evaluating <false substitute>
instead of the above process. If there is a <true substitute>
and <test> returns a true value, <var> is finally bound to
the result of evaluating <true substitute>.
(key <rest list> (<var spec1> <default1> [<test1> [<true substitute1> [<false substitute1>]]]) ... (<var specn> <defaultn> [<testn> [<true substituten> [<false substituten>]]]) [<option>] . [<rest var>]) <var spec> --> <var> | (<var> <keyword>) <option> --> #f | #t <keyword> --> <any scheme object> <default> --> <expression> <test> --> <expression> <true substitute> --> <expression> <false substitute> --> <expression>This
key form is the same as the cat form in view of the fact that both
don't use argument position for binding <var>s to elements of <rest list>.
However, for extracting values from <rest list>, the former uses explicitly
keywords and the latter uses implicitly <test>s. The keywords in this form
are not self-evaluating symbols (keyword objects) but any scheme objects. The
keyword used in <rest list> for the corresponding variable is a symbol of the
same name as the variable of the <var spec> composed of a single <var>. But
the keyword can be any scheme object when the <var spec> is specified as a
parenthesized variable and a keyword.
The elements of <rest list> are sequentially interpreted as a series of pairs,
where the first member of each pair is a keyword and the second is the
corresponding value. If there is no element for a particular keyword, the
<var> is bound to the result of evaluating <default>. When there is a <test>,
it is evaluated only when <var> is bound to an element of <rest list>. If it
returns a false value and there is no <false substitute>, an error is
signaled. If it returns a false value and there is a <false substitute>,
<var> is rebound to the result of evaluating <false substitute> instead of
signaling an error. If it returns a true value and there is a <true
substitute>, <var> is rebound to the result of evaluating <true substitute>.
When there are more elements than ones that are specified by <var spec>s, an
error is signaled. But if <rest var> is given, it is bound to the remaining
elements.
The following options can be used to control binding behavior when the keyword
of keyword-value pair at the bind processing site is different from any
keywords specified by <var spec>s.
#f - the variable is bound to the corresponding <default>.#t - the remaining elements of <rest list> are
continually interpreted as a single element until the element is a
particular keyword.(rec (<var1> <expr1>) (<var2> <expr2>) ...)This is the same as
(letrec[*] ((<var1> <expr1>) (<var2> <expr2>) ...)
(values <var1> <var2> ... <expr>)This is the same as 17.
((values <var1> <var2> ...) <expr>)
((values <var1> ... . <varn>) <expr>)The <expr> should be a
values expression or its
equivalent. The matching of <var>s to the values of
<expr> is as for the matching of <formals> to arguments in a
lambda expression.
((values <var1> <var2> <var3> ...) <expr1> <expr2> <expr3> ...)This is the same as
(let[*] ((<var1> <expr1>) (<var2> <expr2>) (<var3> <expr3>) ...)
((values <var1> ... . <varn>) <expr1> ... <exprn> ...)This is the same as (let[*] ((<var1> <expr1>) ... (<varn> (list <exprn> ...))).
(() <expr1> <expr2> ...)This works as an intervening external environment in
alet, and an intervening internal environment in
alet*.
(alet name (<binding spec> ...) body ...) (alet* name (<binding spec> ...) body ...)
These are the same as the named-let (R5RS, 4.2.4) except
binding specification. These allow all sorts of bindings in <binding
spec>.
(alet ((a (begin (display "1st") 1))
((b c) 2 (begin (display "2nd") 3))
(() (define m #f) (define n (list 8)))
((d (begin (display "3rd") 4))
(key '(e 5 tmp 6) (e 0) ((f 'tmp) 55)) . p)
g (nu (begin (display "4th") 7) n)
((values . h) (apply values 7 (begin (display "5th") n)))
((m 11) (n n) . q)
(rec (i (lambda () (- (j) 1)))
(j (lambda () 10)))
(and (k (begin (display "6th") m))
(l (begin (display "end") (newline) 12)))
(o))
(if (< d 10)
(p 40 50 60)
(if (< m 100)
(q 111 n)
(begin (display (list a b c d e f g h (i) (j) k l m n))
(newline))))
(o (list o p q))
(display "This is not displayed"))
=> 1st2nd3rd4th5th6th#f
(alet* ((a (begin (display "1st") 1))
((b c) 2 (begin (display "2nd") 3))
(() (define m #f) (define n (list 8)))
((d (begin (display "3rd") 4))
(key '(e 5 tmp 6) (e 0) ((f 'tmp) 55)) . p)
g (nu (begin (display "4th") 7) n)
((values . h) (apply values 7 (begin (display "5th") n)))
((m 11) (n n) . q)
(rec (i (lambda () (- (j) 1)))
(j (lambda () 10)))
(and (k (begin (display "6th") m))
(l (begin (display "end") (newline) 12)))
(o))
(if (< d 10)
(p 40 50 60)
(if (< m 100)
(q 111 n)
(begin (display (list a b c d e f g h (i) (j) k l m n))
(newline))))
(o (list o p q))
(display "This is not displayed"))
=> 1st2nd3rd4th5th6thend
4th5th6thend
6thend
(1 2 3 40 50 60 (7 8) (7 8) 9 10 111 12 111 (8))
(#<continuation> #<procedure:p> #<procedure:q>)
(define (arg-message head-message proc . message)
(display head-message) (newline)
(alet ((() . lp)
(() (for-each display message))
(arg (read)))
(if (proc arg) arg (lp))))
(define (substr str . rest)
(alet* ((len (string-length str))
(opt rest
(start 0
(and (integer? start) (<= 0 start len))
start
(arg-message
"The first argument:"
(lambda (n) (and (integer? n) (<= 0 n len)))
"Write number (" 0 " <= number <= " len "): "))
(end len
(and (integer? end) (<= start end len))
end
(arg-message
"The second argument:"
(lambda (n) (and (integer? n) (<= start n len)))
"Write number (" start " <= number <= " len "): "))))
(substring str start end)))
(substr "abcdefghi" 3)
=> "defghi"
(substr "abcdefghi" 3 7)
=> "defg"
(substr "abcdefghi" 20 7)
=> The first argument:
Write number (0 <= number <= 9): 3
"defg"
(substr "abcdefghi" "a" 20)
=> The first argument:
Write number (0 <= number <= 9): 2
The second argument:
Write number (2 <= number <= 9): 10
Write number (2 <= number <= 9): 9
"cdefghi"
The following implementation is written in R5RS hygienic macros and requires SRFI 23 (Error reporting mechanism).
;;; mu & nu
(define-syntax mu
(syntax-rules ()
((mu argument ...)
(lambda (f) (f argument ...)))))
(define-syntax nu
(syntax-rules ()
((nu argument ...)
(lambda (f) (apply f argument ...)))))
;;; alet
(define-syntax alet
(syntax-rules ()
((alet (bn ...) bd ...)
(%alet () () (bn ...) bd ...))
((alet var (bn ...) bd ...)
(%alet (var) () (bn ...) bd ...))))
(define-syntax %alet
(syntax-rules (opt cat key rec and values)
((%alet () ((n v) ...) () bd ...)
((lambda (n ...) bd ...) v ...))
((%alet (var) ((n v) ...) () bd ...)
((letrec ((var (lambda (n ...) bd ...)))
var) v ...))
((%alet (var (p ...) (nv ...) (bn ...)) ((n v) ...) () bd ...)
((letrec ((t (lambda (v ...)
(%alet (p ...) (nv ... (n v) ... (var t))
(bn ...) bd ...))))
t) v ...))
((%alet (p ...) (nv ...) ((() a b ...) bn ...) bd ...)
((lambda () a b ... (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet (p ...) (nv ...) (((a) c) bn ...) bd ...)
((lambda (t) (%alet (p ...) (nv ... (a t)) (bn ...) bd ...)) c))
((%alet (p ...) (nv ...) (((values a) c) bn ...) bd ...)
((lambda (t) (%alet (p ...) (nv ... (a t)) (bn ...) bd ...)) c))
((%alet (p ...) (nv ...) (((values . b) c d ...) bn ...) bd ...)
(%alet "dot" (p ...) (nv ...) (values) (b c d ...) (bn ...) bd ...))
((%alet "dot" (p ...) (nv ...) (values t ...) ((a . b) c ...)
(bn ...) bd ...)
(%alet "dot" (p ...) (nv ... (a tn)) (values t ... tn) (b c ...)
(bn ...) bd ...))
((%alet "dot" (p ...) (nv ...) (values t ...) (() c) (bn ...) bd ...)
(call-with-values (lambda () c)
(lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet "dot" (p ...) (nv ...) (values t ...) (() c ...) (bn ...) bd ...)
((lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...)) c ...))
((%alet "dot" (p ...) (nv ...) (values t ...) (b c) (bn ...) bd ...)
(call-with-values (lambda () c)
(lambda (t ... . tn)
(%alet (p ...) (nv ... (b tn)) (bn ...) bd ...))))
((%alet "dot" (p ...) (nv ...) (values t ...) (b c ...) (bn ...) bd ...)
((lambda (t ... . tn)
(%alet (p ...) (nv ... (b tn)) (bn ...) bd ...)) c ...))
((%alet (p ...) (nv ...) (((a . b) c d ...) bn ...) bd ...)
(%alet "dot" (p ...) (nv ... (a t)) (t) (b c d ...) (bn ...) bd ...))
((%alet "dot" (p ...) (nv ...) (t ...) ((a . b) c ...) (bn ...) bd ...)
(%alet "dot" (p ...) (nv ... (a tn)) (t ... tn) (b c ...) (bn ...)
bd ...))
((%alet "dot" (p ...) (nv ...) (t ...) (() c) (bn ...) bd ...)
(c (lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet "dot" (p ...) (nv ...) (t ...) (() c ...) (bn ...) bd ...)
((lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...)) c ...))
((%alet "dot" (p ...) (nv ...) (t ...) (b c) (bn ...) bd ...)
(c (lambda (t ... . tn) (%alet (p ...) (nv ... (b tn)) (bn ...) bd ...))))
((%alet "dot" (p ...) (nv ...) (t ...) (b c ...) (bn ...) bd ...)
((lambda (t ... . tn)
(%alet (p ...) (nv ... (b tn)) (bn ...) bd ...)) c ...))
((%alet (p ...) (nv ...) ((and (n1 v1 t1 ...) (n2 v2 t2 ...) ...) bn ...)
bd ...)
(%alet "and" (p ...) (nv ...) ((n1 v1 t1 ...) (n2 v2 t2 ...) ...) (bn ...)
bd ...))
((%alet "and" (p ...) (nv ...) ((n v) nvt ...) (bn ...) bd ...)
(let ((t v))
(and t (%alet "and" (p ...) (nv ... (n t)) (nvt ...) (bn ...) bd ...))))
((%alet "and" (p ...) (nv ...) ((n v t) nvt ...) (bn ...) bd ...)
(let ((tt v))
(and (let ((n tt)) t)
(%alet "and" (p ...) (nv ... (n tt)) (nvt ...) (bn ...) bd ...))))
((%alet "and" (p ...) (nv ...) () (bn ...) bd ...)
(%alet (p ...) (nv ...) (bn ...) bd ...))
((%alet (p ...) (nv ...) ((opt z a . e) bn ...) bd ...)
(%alet "opt" (p ...) (nv ...) z (a . e) (bn ...) bd ...))
((%alet "opt" (p ...) (nv ...) z ((n d t ...)) (bn ...) bd ...)
(let ((x (if (null? z)
d
(if (null? (cdr z))
(wow-opt n (car z) t ...)
(error "alet: too many arguments" (cdr z))))))
(%alet (p ...) (nv ... (n x)) (bn ...) bd ...)))
((%alet "opt" (p ...) (nv ...) z ((n d t ...) . e) (bn ...) bd ...)
(let ((y (if (null? z) z (cdr z)))
(x (if (null? z)
d
(wow-opt n (car z) t ...))))
(%alet "opt" (p ...) (nv ... (n x)) y e (bn ...) bd ...)))
((%alet "opt" (p ...) (nv ...) z e (bn ...) bd ...)
(let ((te z))
(%alet (p ...) (nv ... (e te)) (bn ...) bd ...)))
((%alet (p ...) (nv ...) ((cat z a . e) bn ...) bd ...)
(let ((y z))
(%alet "cat" (p ...) (nv ...) y (a . e) (bn ...) bd ...)))
((%alet "cat" (p ...) (nv ...) z ((n d t ...)) (bn ...) bd ...)
(let ((x (if (null? z)
d
(if (null? (cdr z))
(wow-cat-end z n t ...)
(error "alet: too many arguments" (cdr z))))))
(%alet (p ...) (nv ... (n x)) (bn ...) bd ...)))
((%alet "cat" (p ...) (nv ...) z ((n d t ...) . e) (bn ...) bd ...)
(let ((x (if (null? z)
d
(wow-cat! z n d t ...))))
(%alet "cat" (p ...) (nv ... (n x)) z e (bn ...) bd ...)))
((%alet "cat" (p ...) (nv ...) z e (bn ...) bd ...)
(let ((te z))
(%alet (p ...) (nv ... (e te)) (bn ...) bd ...)))
((%alet (p ...) (nv ...) ((key z a . e) bn ...) bd ...)
(let ((y z))
(%alet "key" (p ...) (nv ...) y () () (a . e) () (bn ...) bd ...)))
((%alet "key" (p ...) (nv ...) z ()
(ndt ...) (((n k) d t ...) . e) (kk ...) (bn ...) bd ...)
(%alet "key" (p ...) (nv ...) z ()
(ndt ... ((n k) d t ...)) e (kk ... k) (bn ...) bd ...))
((%alet "key" (p ...) (nv ...) z ()
(ndt ...) ((n d t ...) . e) (kk ...) (bn ...) bd ...)
(%alet "key" (p ...) (nv ...) z ()
(ndt ... ((n 'n) d t ...)) e (kk ... 'n) (bn ...) bd ...))
((%alet "key" (p ...) (nv ...) z ()
(ndt nd ...) (#t . e) (kk k ...) (bn ...) bd ...)
(%alet "key" (p ...) (nv ...) z (#t)
(ndt nd ...) e (kk k ...) (bn ...) bd ...))
((%alet "key" (p ...) (nv ...) z ()
(ndt nd ...) (#f . e) (kk k ...) (bn ...) bd ...)
(%alet "key" (p ...) (nv ...) z (#f)
(ndt nd ...) e (kk k ...) (bn ...) bd ...))
((%alet "key" (p ...) (nv ...) z (o ...)
(((n k) d t ...) ndt ...) e (kk ...) (bn ...) bd ...)
(let ((x (if (null? z)
d
(wow-key! z (o ...) (kk ...) (n k) d t ...))))
(%alet "key" (p ...) (nv ... (n x)) z (o ...)
(ndt ...) e (kk ...) (bn ...) bd ...)))
((%alet "key" (p ...) (nv ...) z (o ...) () () (kk ...) (bn ...) bd ...)
(if (null? z)
(%alet (p ...) (nv ...) (bn ...) bd ...)
(error "alet: too many arguments" z)))
((%alet "key" (p ...) (nv ...) z (o ...) () e (kk ...) (bn ...) bd ...)
(let ((te z)) (%alet (p ...) (nv ... (e te)) (bn ...) bd ...)))
((%alet (p ...) (nv ...) ((rec (n v) (nn vv) ...) bn ...) bd ...)
(%alet "rec" (p ...) (nv ... (n t)) ((n v t))
((nn vv) ...) (bn ...) bd ...))
((%alet "rec" (p ...) (nv ...) (nvt ...) ((n v) (nn vv) ...)
(bn ...) bd ...)
(%alet "rec" (p ...) (nv ... (n t)) (nvt ... (n v t)) ((nn vv) ...)
(bn ...) bd ...))
((%alet "rec" (p ...) (nv ...) ((n v t) ...) () (bn ...) bd ...)
((let ((n '<undefined>) ...)
(let ((t v) ...)
(set! n t) ...
(mu n ...)))
(lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet (p ...) (nv ...) ((a b) bn ...) bd ...)
((lambda (t) (%alet (p ...) (nv ... (a t)) (bn ...) bd ...)) b))
((%alet (p ...) (nv ...) ((values a c) bn ...) bd ...)
((lambda (t) (%alet (p ...) (nv ... (a t)) (bn ...) bd ...)) c))
((%alet (p ...) (nv ...) ((values a b c ...) bn ...) bd ...)
(%alet "not" (p ...) (nv ... (a t)) (values t) (b c ...) (bn ...) bd ...))
((%alet "not" (p ...) (nv ...) (values t ...) (a b c ...) (bn ...) bd ...)
(%alet "not" (p ...) (nv ... (a tn)) (values t ... tn) (b c ...)
(bn ...) bd ...))
((%alet "not" (p ...) (nv ...) (values t ...) (z) (bn ...) bd ...)
(call-with-values (lambda () z)
(lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet (p ...) (nv ...) ((a b c ...) bn ...) bd ...)
(%alet "not" (p ...) (nv ... (a t)) (t) (b c ...) (bn ...) bd ...))
((%alet "not" (p ...) (nv ...) (t ...) (a b c ...) (bn ...) bd ...)
(%alet "not" (p ...) (nv ... (a tn)) (t ... tn) (b c ...) (bn ...)
bd ...))
((%alet "not" (p ...) (nv ...) (t ...) (z) (bn ...) bd ...)
(z (lambda (t ...) (%alet (p ...) (nv ...) (bn ...) bd ...))))
((%alet (p ...) (nv ...) ((a) bn ...) bd ...)
(call-with-current-continuation
(lambda (t) (%alet (p ...) (nv ... (a t)) (bn ...) bd ...))))
((%alet (p ...) (nv ...) ((a . b) bn ...) bd ...)
(%alet "rot" (p ...) (nv ...) (a) b (bn ...) bd ...))
((%alet "rot" (p ...) (nv ...) (new-bn ...) (a . b) (bn ...) bd ...)
(%alet "rot" (p ...) (nv ...) (new-bn ... a) b (bn ...) bd ...))
((%alet "rot" (p ...) (nv ...) (()) b (bn ...) bd ...)
(%alet (b (p ...) (nv ...) (bn ...)) () () bd ...))
((%alet "rot" (p ...) (nv ...) (new-bn ...) b (bn ...) bd ...)
(%alet (b (p ...) (nv ...) (bn ...)) () (new-bn ...) bd ...))
((%alet (p ...) (nv ...) (a b bn ...) bd ...)
(b (lambda t (%alet (p ...) (nv ... (a t)) (bn ...) bd ...))))))
;;; alet*
(define-syntax alet*
(syntax-rules (opt cat key rec and values)
((alet* () bd ...)
((lambda () bd ...)))
((alet* ((() a b ...) bn ...) bd ...)
((lambda () a b ... (alet* (bn ...) bd ...))))
((alet* (((a) c) bn ...) bd ...)
((lambda (a) (alet* (bn ...) bd ...)) c))
((alet* (((values a) c) bn ...) bd ...)
((lambda (a) (alet* (bn ...) bd ...)) c))
((alet* (((values . b) c) bn ...) bd ...)
(call-with-values (lambda () c)
(lambda* b (alet* (bn ...) bd ...))))
((alet* (((values . b) c d ...) bn ...) bd ...)
(alet* "dot" (b c d ...) (bn ...) bd ...))
((alet* "dot" ((a . b) c d ...) (bn ...) bd ...)
((lambda (a) (alet* "dot" (b d ...) (bn ...) bd ...)) c))
((alet* "dot" (()) (bn ...) bd ...)
(alet* (bn ...) bd ...))
((alet* "dot" (b c ...) (bn ...) bd ...)
((lambda b (alet* (bn ...) bd ...)) c ...))
((alet* (((a . b) c) bn ...) bd ...)
(c (lambda* (a . b) (alet* (bn ...) bd ...))))
((alet* (((a . b) c d ...) bn ...) bd ...)
((lambda (a) (alet* "dot" (b d ...) (bn ...) bd ...)) c))
((alet* ((and (n1 v1 t1 ...) (n2 v2 t2 ...) ...) bn ...) bd ...)
(alet-and* ((n1 v1 t1 ...) (n2 v2 t2 ...) ...) (alet* (bn ...) bd ...)))
((alet* ((opt z a . e) bn ...) bd ...)
(%alet-opt* z (a . e) (alet* (bn ...) bd ...)))
((alet* ((cat z a . e) bn ...) bd ...)
(let ((y z))
(%alet-cat* y (a . e) (alet* (bn ...) bd ...))))
((alet* ((key z a . e) bn ...) bd ...)
(let ((y z))
(%alet-key* y () () (a . e) () (alet* (bn ...) bd ...))))
((alet* ((rec (n1 v1) (n2 v2) ...) bn ...) bd ...)
(alet-rec* ((n1 v1) (n2 v2) ...) (alet* (bn ...) bd ...)))
((alet* ((a b) bn ...) bd ...)
((lambda (a) (alet* (bn ...) bd ...)) b))
((alet* ((values a c) bn ...) bd ...)
((lambda (a) (alet* (bn ...) bd ...)) c))
((alet* ((values a b c ...) bn ...) bd ...)
(alet* "not" (values a) (b c ...) (bn ...) bd ...))
((alet* "not" (values r ...) (a b c ...) (bn ...) bd ...)
(alet* "not" (values r ... a) (b c ...) (bn ...) bd ...))
((alet* "not" (values r ...) (z) (bn ...) bd ...)
(call-with-values (lambda () z)
(lambda* (r ...) (alet* (bn ...) bd ...))))
((alet* ((a b c ...) bn ...) bd ...)
(alet* "not" (a) (b c ...) (bn ...) bd ...))
((alet* "not" (r ...) (a b c ...) (bn ...) bd ...)
(alet* "not" (r ... a) (b c ...) (bn ...) bd ...))
((alet* "not" (r ...) (z) (bn ...) bd ...)
(z (lambda* (r ...) (alet* (bn ...) bd ...))))
((alet* ((a) bn ...) bd ...)
(call-with-current-continuation (lambda (a) (alet* (bn ...) bd ...))))
((alet* ((a . b) bn ...) bd ...)
(%alet* () () ((a . b) bn ...) bd ...))
((alet* (a b bn ...) bd ...)
(b (lambda a (alet* (bn ...) bd ...))))
((alet* var (bn ...) bd ...)
(%alet* (var) () (bn ...) bd ...))))
(define-syntax %alet*
(syntax-rules (opt cat key rec and values)
((%alet* (var) (n ...) () bd ...)
((letrec ((var (lambda* (n ...) bd ...)))
var) n ...))
((%alet* (var (bn ...)) (n ...) () bd ...)
((letrec ((var (lambda* (n ...) (alet* (bn ...) bd ...))))
var) n ...))
((%alet* (var (p ...) (nn ...) (bn ...)) (n ...) () bd ...)
((letrec ((var (lambda* (n ...)
(%alet* (p ...) (nn ... n ... var) (bn ...)
bd ...))))
var) n ...))
((%alet* (p ...) (n ...) ((() a b ...) bn ...) bd ...)
((lambda () a b ... (%alet* (p ...) (n ...) (bn ...) bd ...))))
((%alet* (p ...) (n ...) (((a) c) bn ...) bd ...)
((lambda (a) (%alet* (p ...) (n ... a) (bn ...) bd ...)) c))
((%alet* (p ...) (n ...) (((values a) c) bn ...) bd ...)
((lambda (a) (%alet* (p ...) (n ... a) (bn ...) bd ...)) c))
((%alet* (p ...) (n ...) (((values . b) c) bn ...) bd ...)
(%alet* "one" (p ...) (n ...) (values) (b c) (bn ...) bd ...))
((%alet* "one" (p ...) (n ...) (values r ...) ((a . b) c) (bn ...) bd ...)
(%alet* "one" (p ...) (n ... a) (values r ... a) (b c) (bn ...) bd ...))
((%alet* "one" (p ...) (n ...) (values r ...) (() c) (bn ...) bd ...)
(call-with-values (lambda () c)
(lambda* (r ...) (%alet* (p ...) (n ...) (bn ...) bd ...))))
((%alet* "one" (p ...) (n ...) (values r ...) (b c) (bn ...) bd ...)
(call-with-values (lambda () c)
(lambda* (r ... . b) (%alet* (p ...) (n ... b) (bn ...) bd ...))))
((%alet* (p ...) (n ...) (((values . b) c d ...) bn ...) bd ...)
(%alet* "dot" (p ...) (n ...) (b c d ...) (bn ...) bd ...))
((%alet* (p ...) (n ...) (((a . b) c) bn ...) bd ...)
(%alet* "one" (p ...) (n ... a) (a) (b c) (bn ...) bd ...))
((%alet* "one" (p ...) (n ...) (r ...) ((a . b) c) (bn ...) bd ...)
(%alet* "one" (p ...) (n ... a) (r ... a) (b c) (bn ...) bd ...))
((%alet* "one" (p ...) (n ...) (r ...) (() c) (bn ...) bd ...)
(c (lambda* (r ...) (%alet* (p ...) (n ...) (bn ...) bd ...))))
((%alet* "one" (p ...) (n ...) (r ...) (b c) (bn ...) bd ...)
(c (lambda* (r ... . b) (%alet* (p ...) (n ... b) (bn ...) bd ...))))
((%alet* (p ...) (n ...) (((a . b) c d ...) bn ...) bd ...)
((lambda (a)
(%alet* "dot" (p ...) (n ... a) (b d ...) (bn ...) bd ...)) c))
((%alet* "dot" (p ...) (n ...) ((a . b) c d ...) (bn ...) bd ...)
((lambda (a)
(%alet* "dot" (p ...) (n ... a) (b d ...) (bn ...) bd ...)) c))
((%alet* "dot" (p ...) (n ...) (()) (bn ...) bd ...)
(%alet* (p ...) (n ...) (bn ...) bd ...))
((%alet* "dot" (p ...) (n ...) (b c ...) (bn ...) bd ...)
((lambda b (%alet* (p ...) (n ... b) (bn ...) bd ...)) c ...))
((%alet* (p ...) (n ...) ((and (n1 v1 t1 ...) (n2 v2 t2 ...) ...) bn ...)
bd ...)
(alet-and* ((n1 v1 t1 ...) (n2 v2 t2 ...) ...)
(%alet* (p ...) (n ... n1 n2 ...) (bn ...) bd ...)))
((%alet* (p ...) (n ...) ((opt z a . e) bn ...) bd ...)
(%alet* "opt" (p ...) (n ...) z (a . e) (bn ...) bd ...))
((%alet* "opt" (p ...) (nn ...) z ((n d t ...)) (bn ...) bd ...)
(let ((n (if (null? z)
d
(if (null? (cdr z))
(wow-opt n (car z) t ...)
(error "alet*: too many arguments" (cdr z))))))
(%alet* (p ...) (nn ... n) (bn ...) bd ...)))
((%alet* "opt" (p ...) (nn ...) z ((n d t ...) . e) (bn ...) bd ...)
(let ((y (if (null? z) z (cdr z)))
(n (if (null? z)
d
(wow-opt n (car z) t ...))))
(%alet* "opt" (p ...) (nn ... n) y e (bn ...) bd ...)))
((%alet* "opt" (p ...) (nn ...) z e (bn ...) bd ...)
(let ((e z))
(%alet* (p ...) (nn ... e) (bn ...) bd ...)))
((%alet* (p ...) (nn ...) ((cat z a . e) bn ...) bd ...)
(let ((y z))
(%alet* "cat" (p ...) (nn ...) y (a . e) (bn ...) bd ...)))
((%alet* "cat" (p ...) (nn ...) z ((n d t ...)) (bn ...) bd ...)
(let ((n (if (null? z)
d
(if (null? (cdr z))
(wow-cat-end z n t ...)
(error "alet*: too many arguments" (cdr z))))))
(%alet* (p ...) (nn ... n) (bn ...) bd ...)))
((%alet* "cat" (p ...) (nn ...) z ((n d t ...) . e) (bn ...) bd ...)
(let ((n (if (null? z)
d
(wow-cat! z n d t ...))))
(%alet* "cat" (p ...) (nn ... n) z e (bn ...) bd ...)))
((%alet* "cat" (p ...) (nn ...) z e (bn ...) bd ...)
(let ((e z))
(%alet* (p ...) (nn ... e) (bn ...) bd ...)))
((%alet* (p ...) (m ...) ((key z a . e) bn ...) bd ...)
(let ((y z))
(%alet* "key" (p ...) (m ...) y () () (a . e) () (bn ...) bd ...)))
((%alet* "key" (p ...) (m ...) z ()
(ndt ...) (((n k) d t ...) . e) (kk ...) (bn ...) bd ...)
(%alet* "key" (p ...) (m ...) z ()
(ndt ... ((n k) d t ...)) e (kk ... k) (bn ...) bd ...))
((%alet* "key" (p ...) (m ...) z ()
(ndt ...) ((n d t ...) . e) (kk ...) (bn ...) bd ...)
(%alet* "key" (p ...) (m ...) z ()
(ndt ... ((n 'n) d t ...)) e (kk ... 'n) (bn ...) bd ...))
((%alet* "key" (p ...) (m ...) z ()
(ndt nd ...) (#t . e) (kk k ...) (bn ...) bd ...)
(%alet* "key" (p ...) (m ...) z (#t)
(ndt nd ...) e (kk k ...) (bn ...) bd ...))
((%alet* "key" (p ...) (m ...) z ()
(ndt nd ...) (#f . e) (kk k ...) (bn ...) bd ...)
(%alet* "key" (p ...) (m ...) z (#f)
(ndt nd ...) e (kk k ...) (bn ...) bd ...))
((%alet* "key" (p ...) (m ...) z (o ...)
(((n k) d t ...) ndt ...) e (kk ...) (bn ...) bd ...)
(let ((n (if (null? z)
d
(wow-key! z (o ...) (kk ...) (n k) d t ...))))
(%alet* "key" (p ...) (m ... n) z (o ...)
(ndt ...) e (kk ...) (bn ...) bd ...)))
((%alet* "key" (p ...) (m ...) z (o ...) () () (kk ...) (bn ...) bd ...)
(if (null? z)
(%alet* (p ...) (m ...) (bn ...) bd ...)
(error "alet*: too many arguments" z)))
((%alet* "key" (p ...) (m ...) z (o ...) () e (kk ...) (bn ...) bd ...)
(let ((e z)) (%alet* (p ...) (m ... e) (bn ...) bd ...)))
((%alet* (p ...) (n ...) ((rec (n1 v1) (n2 v2) ...) bn ...) bd ...)
(alet-rec* ((n1 v1) (n2 v2) ...)
(%alet* (p ...) (n ... n1 n2 ...) (bn ...) bd ...)))
((%alet* (p ...) (n ...) ((a b) bn ...) bd ...)
((lambda (a) (%alet* (p ...) (n ... a) (bn ...) bd ...)) b))
((%alet* (p ...) (n ...) ((values a c) bn ...) bd ...)
((lambda (a) (%alet* (p ...) (n ... a) (bn ...) bd ...)) c))
((%alet* (p ...) (n ...) ((values a b c ...) bn ...) bd ...)
(%alet* "not" (p ...) (n ... a) (values a) (b c ...) (bn ...) bd ...))
((%alet* "not" (p ...) (n ...) (values r ...) (a b c ...) (bn ...) bd ...)
(%alet* "not" (p ...) (n ... a) (values r ... a) (b c ...) (bn ...)
bd ...))
((%alet* "not" (p ...) (n ...) (values r ...) (z) (bn ...) bd ...)
(call-with-values (lambda () z)
(lambda* (r ...) (%alet* (p ...) (n ...) (bn ...) bd ...))))
((%alet* (p ...) (n ...) ((a b c ...) bn ...) bd ...)
(%alet* "not" (p ...) (n ... a) (a) (b c ...) (bn ...) bd ...))
((%alet* "not" (p ...) (n ...) (r ...) (a b c ...) (bn ...) bd ...)
(%alet* "not" (p ...) (n ... a) (r ... a) (b c ...) (bn ...) bd ...))
((%alet* "not" (p ...) (n ...) (r ...) (z) (bn ...) bd ...)
(z (lambda* (r ...) (%alet* (p ...) (n ...) (bn ...) bd ...))))
((%alet* (p ...) (n ...) ((a) bn ...) bd ...)
(call-with-current-continuation
(lambda (a) (%alet* (p ...) (n ... a) (bn ...) bd ...))))
((%alet* (p ...) (n ...) ((a . b) bn ...) bd ...)
(%alet* "rot" (p ...) (n ...) (a) b (bn ...) bd ...))
((%alet* "rot" (p ...) (n ...) (new-bn ...) (a . b) (bn ...) bd ...)
(%alet* "rot" (p ...) (n ...) (new-bn ... a) b (bn ...) bd ...))
((%alet* "rot" () () (()) b (bn ...) bd ...)
(%alet* (b (bn ...)) () () bd ...))
((%alet* "rot" (p ...) (n ...) (()) b (bn ...) bd ...)
(%alet* (b (p ...) (n ...) (bn ...)) () () bd ...))
((%alet* "rot" () () (new-bn ...) b (bn ...) bd ...)
(%alet* (b (bn ...)) () (new-bn ...) bd ...))
((%alet* "rot" (p ...) (n ...) (new-bn ...) b (bn ...) bd ...)
(%alet* (b (p ...) (n ...) (bn ...)) () (new-bn ...) bd ...))
((%alet* (p ...) (n ...) (a b bn ...) bd ...)
(b (lambda a (%alet* (p ...) (n ... a) (bn ...) bd ...))))))
;;; auxiliaries
(define-syntax lambda*
(syntax-rules ()
((lambda* (a . e) bd ...)
(lambda* "star" (ta) (a) e bd ...))
((lambda* "star" (t ...) (n ...) (a . e) bd ...)
(lambda* "star" (t ... ta) (n ... a) e bd ...))
((lambda* "star" (t ...) (n ...) () bd ...)
(lambda (t ...)
(let* ((n t) ...) bd ...)))
((lambda* "star" (t ...) (n ...) e bd ...)
(lambda (t ... . te)
(let* ((n t) ... (e te)) bd ...)))
((lambda* e bd ...)
(lambda e bd ...))))
(define-syntax alet-and
(syntax-rules ()
((alet-and ((n v t ...) ...) bd ...)
(alet-and "and" () ((n v t ...) ...) bd ...))
((alet-and "and" (nt ...) ((n v) nvt ...) bd ...)
(let ((t v))
(and t (alet-and "and" (nt ... (n t)) (nvt ...) bd ...))))
((alet-and "and" (nt ...) ((n v t) nvt ...) bd ...)
(let ((tt v))
(and (let ((n tt)) t)
(alet-and "and" (nt ... (n tt)) (nvt ...) bd ...))))
((alet-and "and" ((n t) ...) () bd ...)
((lambda (n ...) bd ...) t ...))))
(define-syntax alet-and*
(syntax-rules ()
((alet-and* () bd ...)
((lambda () bd ...)))
((alet-and* ((n v) nvt ...) bd ...)
(let ((n v))
(and n (alet-and* (nvt ...) bd ...))))
((alet-and* ((n v t) nvt ...) bd ...)
(let ((n v))
(and t (alet-and* (nvt ...) bd ...))))))
(define-syntax alet-rec
(syntax-rules ()
((alet-rec ((n v) ...) bd ...)
(alet-rec "rec" () ((n v) ...) bd ...))
((alet-rec "rec" (nvt ...) ((n v) nv ...) bd ...)
(alet-rec "rec" (nvt ... (n v t)) (nv ...) bd ...))
((alet-rec "rec" ((n v t) ...) () bd ...)
(let ((n '<undefined>) ...)
(let ((t v) ...)
(set! n t) ...
;;(let ()
;; bd ...))))))
bd ...)))))
(define-syntax alet-rec*
(syntax-rules ()
((alet-rec* ((n v) ...) bd ...)
(let* ((n '<undefined>) ...)
(set! n v) ...
;;(let ()
;; bd ...)))))
bd ...))))
(define-syntax wow-opt
(syntax-rules ()
((wow-opt n v)
v)
((wow-opt n v t)
(let ((n v))
(if t n (error "alet[*]: bad argument" n 'n 't))))
((wow-opt n v t ts)
(let ((n v))
(if t ts (error "alet[*]: bad argument" n 'n 't))))
((wow-opt n v t ts fs)
(let ((n v))
(if t ts fs)))))
(define-syntax wow-opt!
(syntax-rules ()
((wow-opt! z n)
(let ((n (car z)))
(set! z (cdr z))
n))
((wow-opt! z n t)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) n)
(error "alet[*]: bad argument" n 'n 't))))
((wow-opt! z n t ts)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) ts)
(error "alet[*]: bad argument" n 'n 't))))
((wow-opt! z n t ts fs)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) ts)
(begin (set! z (cdr z)) fs))))))
(define-syntax wow-cat-end
(syntax-rules ()
((wow-cat-end z n)
(car z))
((wow-cat-end z n t)
(let ((n (car z)))
(if t n (error "alet[*]: too many argument" z))))
((wow-cat-end z n t ts)
(let ((n (car z)))
(if t ts (error "alet[*]: too many argument" z))))
((wow-cat-end z n t ts fs)
(let ((n (car z)))
(if t ts fs)))))
(define-syntax wow-cat
(syntax-rules ()
((wow-cat z n d)
z)
((wow-cat z n d t)
(let ((n (car z)))
(if t
z
(let lp ((head (list n)) (tail (cdr z)))
(if (null? tail)
(cons d z)
(let ((n (car tail)))
(if t
(cons n (append (reverse head) (cdr tail)))
(lp (cons n head) (cdr tail)))))))))
((wow-cat z n d t ts)
(let ((n (car z)))
(if t
(cons ts (cdr z))
(let lp ((head (list n)) (tail (cdr z)))
(if (null? tail)
(cons d z)
(let ((n (car tail)))
(if t
(cons ts (append (reverse head) (cdr tail)))
(lp (cons n head) (cdr tail)))))))))
((wow-cat z n d t ts fs)
(let ((n (car z)))
(if t
(cons ts (cdr z))
(cons fs (cdr z)))))))
(define-syntax wow-cat!
(syntax-rules ()
((wow-cat! z n d)
(let ((n (car z)))
(set! z (cdr z))
n))
((wow-cat! z n d t)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) n)
(let lp ((head (list n)) (tail (cdr z)))
(if (null? tail)
d
(let ((n (car tail)))
(if t
(begin (set! z (append (reverse head) (cdr tail))) n)
(lp (cons n head) (cdr tail)))))))))
((wow-cat! z n d t ts)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) ts)
(let lp ((head (list n)) (tail (cdr z)))
(if (null? tail)
d
(let ((n (car tail)))
(if t
(begin (set! z (append (reverse head) (cdr tail))) ts)
(lp (cons n head) (cdr tail)))))))))
((wow-cat! z n d t ts fs)
(let ((n (car z)))
(if t
(begin (set! z (cdr z)) ts)
(begin (set! z (cdr z)) fs))))))
(define-syntax wow-key!
(syntax-rules ()
((wow-key! z () (kk ...) (n key) d)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (cdr y)) (car y))
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (append (reverse head) (cdr y)))
(car y))
(lp (cons (car y) (cons x head))
(cdr y)))))))))))
((wow-key! z (#f) (kk ...) (n key) d)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (cdr y)) (car y))
(let ((lk (list kk ...)))
(if (not (member x lk))
d
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (append (reverse head)
(cdr y)))
(car y))
(if (not (member x lk))
d
(lp (cons (car y) (cons x head))
(cdr y))))))))))))))
((wow-key! z (#t) (kk ...) (n key) d)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (cdr y)) (car y))
(let* ((lk (list kk ...))
(m (member x lk)))
(let lp ((head (if m (list (car y) x) (list x)))
(tail (if m (cdr y) y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(begin (set! z (append (reverse head)
(cdr y)))
(car y))
(let ((m (member x lk)))
(lp (if m
(cons (car y) (cons x head))
(cons x head))
(if m (cdr y) y)))))))))))))
((wow-key! z () (kk ...) (n key) d t)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) n)
(error "alet[*]: bad argument" n 'n 't)))
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
n)
(error "alet[*]: bad argument"
n 'n 't)))
(lp (cons (car y) (cons x head))
(cdr y)))))))))))
((wow-key! z (#f) (kk ...) (n key) d t)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) n)
(error "alet[*]: bad argument" n 'n 't)))
(let ((lk (list kk ...)))
(if (not (member x lk))
d
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin
(set! z (append (reverse head)
(cdr y)))
n)
(error "alet[*]: bad argument"
n 'n 't)))
(if (not (member x lk))
d
(lp (cons (car y) (cons x head))
(cdr y))))))))))))))
((wow-key! z (#t) (kk ...) (n key) d t)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) n)
(error "alet[*]: bad argument" n 'n 't)))
(let* ((lk (list kk ...))
(m (member x lk)))
(let lp ((head (if m (list (car y) x) (list x)))
(tail (if m (cdr y) y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
n)
(error "alet[*]: bad argument"
n 'n 't)))
(let ((m (member x lk)))
(lp (if m
(cons (car y) (cons x head))
(cons x head))
(if m (cdr y) y)))))))))))))
((wow-key! z () (kk ...) (n key) d t ts)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(error "alet[*]: bad argument" n 'n 't)))
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
ts)
(error "alet[*]: bad argument"
n 'n 't)))
(lp (cons (car y) (cons x head))
(cdr y)))))))))))
((wow-key! z (#f) (kk ...) (n key) d t ts)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(error "alet[*]: bad argument" n 'n 't)))
(let ((lk (list kk ...)))
(if (not (member x lk))
d
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin
(set! z (append (reverse head)
(cdr y)))
ts)
(error "alet[*]: bad argument"
n 'n 't)))
(if (not (member x lk))
d
(lp (cons (car y) (cons x head))
(cdr y))))))))))))))
((wow-key! z (#t) (kk ...) (n key) d t ts)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(error "alet[*]: bad argument" n 'n 't)))
(let* ((lk (list kk ...))
(m (member x lk)))
(let lp ((head (if m (list (car y) x) (list x)))
(tail (if m (cdr y) y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
ts)
(error "alet[*]: bad argument"
n 'n 't)))
(let ((m (member x lk)))
(lp (if m
(cons (car y) (cons x head))
(cons x head))
(if m (cdr y) y)))))))))))))
((wow-key! z () (kk ...) (n key) d t ts fs)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(begin (set! z (cdr y)) fs)))
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
ts)
(begin (set! z (append (reverse head)
(cdr y)))
fs)))
(lp (cons (car y) (cons x head))
(cdr y)))))))))))
((wow-key! z (#f) (kk ...) (n key) d t ts fs)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(begin (set! z (cdr y)) fs)))
(let ((lk (list kk ...)))
(if (not (member x lk))
d
(let lp ((head (list (car y) x)) (tail (cdr y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin
(set! z (append (reverse head)
(cdr y)))
ts)
(begin
(set! z (append (reverse head)
(cdr y)))
fs)))
(if (not (member x lk))
d
(lp (cons (car y) (cons x head))
(cdr y))))))))))))))
((wow-key! z (#t) (kk ...) (n key) d t ts fs)
(let ((x (car z))
(y (cdr z)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (cdr y)) ts)
(begin (set! z (cdr y)) fs)))
(let* ((lk (list kk ...))
(m (member x lk)))
(let lp ((head (if m (list (car y) x) (list x)))
(tail (if m (cdr y) y)))
(if (null? tail)
d
(let ((x (car tail))
(y (cdr tail)))
(if (null? y)
d
(if (equal? key x)
(let ((n (car y)))
(if t
(begin (set! z (append (reverse head)
(cdr y)))
ts)
(begin (set! z (append (reverse head)
(cdr y)))
fs)))
(let ((m (member x lk)))
(lp (if m
(cons (car y) (cons x head))
(cons x head))
(if m (cdr y) y)))))))))))))))
(define-syntax alet-opt*
(syntax-rules ()
((alet-opt* z (a . e) bd ...)
(let ((y z))
(%alet-opt* y (a . e) bd ...)))))
(define-syntax %alet-opt*
(syntax-rules ()
((%alet-opt* z ((n d t ...)) bd ...)
(let ((n (if (null? z)
d
(if (null? (cdr z))
(wow-opt n (car z) t ...)
(error "alet*: too many arguments" (cdr z))))))
bd ...))
((%alet-opt* z ((n d t ...) . e) bd ...)
(let ((y (if (null? z) z (cdr z)))
(n (if (null? z)
d
(wow-opt n (car z) t ...))))
(%alet-opt* y e bd ...)))
((%alet-opt* z e bd ...)
(let ((e z)) bd ...))))
;; (define-syntax %alet-opt*
;; (syntax-rules ()
;; ((%alet-opt* z ((n d t ...)) bd ...)
;; (let ((n (if (null? z)
;; d
;; (if (null? (cdr z))
;; (wow-opt n (car z) t ...)
;; (error "alet*: too many arguments" (cdr z))))))
;; bd ...))
;; ((%alet-opt* z ((n d t ...) . e) bd ...)
;; (let ((n (if (null? z)
;; d
;; (wow-opt! z n t ...))))
;; (%alet-opt* z e bd ...)))
;; ((%alet-opt* z e bd ...)
;; (let ((e z)) bd ...))))
;; (define-syntax %alet-opt*
;; (syntax-rules ()
;; ((%alet-opt* z (ndt ...) (a . e) bd ...)
;; (%alet-opt* z (ndt ... a) e bd ...))
;; ((%alet-opt* z ((n d t ...) (nn dd tt ...) ...) () bd ...)
;; (if (null? z)
;; (let* ((n d) (nn dd) ...) bd ...)
;; (let ((y (cdr z))
;; (n (wow-opt n (car z) t ...)))
;; (%alet-opt* y ((nn dd tt ...) ...) () bd ...))))
;; ((%alet-opt* z () () bd ...)
;; (if (null? z)
;; (let () bd ...)
;; (error "alet*: too many arguments" z)))
;; ((%alet-opt* z ((n d t ...) (nn dd tt ...) ...) e bd ...)
;; (if (null? z)
;; (let* ((n d) (nn dd) ... (e z)) bd ...)
;; (let ((y (cdr z))
;; (n (wow-opt n (car z) t ...)))
;; (%alet-opt* y ((nn dd tt ...) ...) e bd ...))))
;; ((%alet-opt* z () e bd ...)
;; (let ((e z)) bd ...))))
(define-syntax alet-cat*
(syntax-rules ()
((alet-cat* z (a . e) bd ...)
(let ((y z))
(%alet-cat* y (a . e) bd ...)))))
;; (define-syntax %alet-cat*
;; (syntax-rules ()
;; ((%alet-cat* z ((n d t ...)) bd ...)
;; (let ((n (if (null? z)
;; d
;; (if (null? (cdr z))
;; (wow-cat-end z n t ...)
;; (error "alet*: too many arguments" (cdr z))))))
;; bd ...))
;; ((%alet-cat* z ((n d t ...) . e) bd ...)
;; (let* ((w (if (null? z)
;; (cons d z)
;; (wow-cat z n d t ...)))
;; (n (car w))
;; (y (cdr w)))
;; (%alet-cat* y e bd ...)))
;; ((%alet-cat* z e bd ...)
;; (let ((e z)) bd ...))))
(define-syntax %alet-cat*
(syntax-rules ()
((%alet-cat* z ((n d t ...)) bd ...)
(let ((n (if (null? z)
d
(if (null? (cdr z))
(wow-cat-end z n t ...)
(error "alet*: too many arguments" (cdr z))))))
bd ...))
((%alet-cat* z ((n d t ...) . e) bd ...)
(let ((n (if (null? z)
d
(wow-cat! z n d t ...))))
(%alet-cat* z e bd ...)))
((%alet-cat* z e bd ...)
(let ((e z)) bd ...))))
;; (define-syntax %alet-cat*
;; (syntax-rules ()
;; ((%alet-cat* z (ndt ...) (a . e) bd ...)
;; (%alet-cat* z (ndt ... a) e bd ...))
;; ((%alet-cat* z ((n d t ...) (nn dd tt ...) ...) () bd ...)
;; (if (null? z)
;; (let* ((n d) (nn dd) ...) bd ...)
;; (let* ((w (wow-cat z n d t ...))
;; (n (car w))
;; (y (cdr w)))
;; (%alet-cat* y ((nn dd tt ...) ...) () bd ...))))
;; ((%alet-cat* z () () bd ...)
;; (if (null? z)
;; (let () bd ...)
;; (error "alet*: too many arguments" z)))
;; ((%alet-cat* z ((n d t ...) (nn dd tt ...) ...) e bd ...)
;; (if (null? z)
;; (let* ((n d) (nn dd) ... (e z)) bd ...)
;; (let* ((w (wow-cat z n d t ...))
;; (n (car w))
;; (y (cdr w)))
;; (%alet-cat* y ((nn dd tt ...) ...) e bd ...))))
;; ((%alet-cat* z () e bd ...)
;; (let ((e z)) bd ...))))
(define-syntax alet-key*
(syntax-rules ()
((alet-key* z (a . e) bd ...)
(let ((y z))
(%alet-key* y () () (a . e) () bd ...)))))
(define-syntax %alet-key*
(syntax-rules ()
((%alet-key* z () (ndt ...) (((n k) d t ...) . e) (kk ...) bd ...)
(%alet-key* z () (ndt ... ((n k) d t ...)) e (kk ... k) bd ...))
((%alet-key* z () (ndt ...) ((n d t ...) . e) (kk ...) bd ...)
(%alet-key* z () (ndt ... ((n 'n) d t ...)) e (kk ... 'n) bd ...))
((%alet-key* z () (ndt nd ...) (#f . e) (kk k ...) bd ...)
(%alet-key* z (#f) (ndt nd ...) e (kk k ...) bd ...))
((%alet-key* z () (ndt nd ...) (#t . e) (kk k ...) bd ...)
(%alet-key* z (#t) (ndt nd ...) e (kk k ...) bd ...))
((%alet-key* z (o ...) (((n k) d t ...) ndt ...) e (kk ...) bd ...)
(let ((n (if (null? z)
d
(wow-key! z (o ...) (kk ...) (n k) d t ...))))
(%alet-key* z (o ...) (ndt ...) e (kk ...) bd ...)))
((%alet-key* z (o ...) () () (kk ...) bd ...)
(if (null? z)
(let () bd ...)
(error "alet*: too many arguments" z)))
((%alet-key* z (o ...) () e (kk ...) bd ...)
(let ((e z)) bd ...))))
and-let*: and and with local bindings, a guarded
let* special form.
Linklet-syntax for multiple values.
LinkCopyright (c) 2006 Joo ChurlSoo.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.