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let-keywords

This page is part of the web mail archives of SRFI 86 from before July 7th, 2015. The new archives for SRFI 86 contain all messages, not just those from before July 7th, 2015.

I've integrated LET-KEYWORDS and LET-KEYWORDS* into the ALET and ALET*
with a syntactic keyword `key'.  They use simple symbols as keywords.

Examples:

(define rest '(a 10 a 30 c 20 40))

(alet* ((key rest (a 1) (b 2 (< a b)) . c)) (list a b c))
=> error: duplicate keysymbol a

(alet* ((key rest allow-duplicate-keys
	     (a 1) (b 2 (< a b)) . c)) (list a b c))
=> error: unknown keysymbol c

(alet* ((key rest allow-duplicate-keys allow-other-keys
	    (a 1) (b 2 (< a b)) . c)) (list a b c))
=> error: no keysymbol 40

(alet* ((key rest allow-duplicate-keys allow-other-keys allow-non-keys
	    (a 1) (b 2 (< a b)) . c)) (list a b c))
=> (10 2 (a 30 c 20 40))

(alet* ((key rest #t (a 1) (b 2 (< a b)) . c)) (list a b c))
=> (10 2 (a 30 c 20 40))

((lambda (m . n)
      (alet* ((opt n (a 10) (b 20) (c 30) . d)
	      (key d (x 100) (y 200) ((a z) 300)))
       (list m a b c x y)))
    0 1 2 3 'z 30 'y 20 'x 10)
=> (0 30 2 3 10 20)

((lambda (m . n)
      (alet* ((key n (x 100) (y 200) ((a z) 300) . d)
	      (opt d (a 10) (b 20) (c 30)))
       (list m a b c x y)))
    0 'z 30 'y 20 'x 10 1 2 3)
=> (0 1 2 3 10 20)

--
Joo ChurlSoo