sunterlib/s48/krims -- Odds and Ends
structure SRFI-1+ -- SRFI-1 + REST
The structure SRFI-1+ extends the list lib with REST := CDR. [ I dearly
like (FIRST . REST) lists and (CAR . CDR) trees. ]
*
structure SRFI-9+ -- SRFI-9 + DEFINE-RECORD-DISCLOSER
The structure SRFI-9+ extends SRFI-9 by the convenient record disclosing
facility from DEFINE-RECORD-TYPES:
(define-record-type rt <make> predicate <field spec> ...) SYNTAX
just as SRFI-9.
(define-record-discloser rt d) --> unspecified PROCEDURE
just as DEFINE-RECORD-TYPES: Install the procedure D : rt -> list
as discloser for records of type RT where RT has been defined with
DEFINE-RECORD-TYPE (from above) and D maps its input record to a
printable list starting with a symbol.
*
structure KRIMS -- Odds and Ends
The structure KRIMS gathers miscellaneous tiny utilities mainly for use
of other sunterlib projects.
(assert exp x0 ...) SYNTAX
Signal an error if EXP is false, reporting both the failed assertion EXP
(literally) and the values of X0 ... Don't evaluate X0 ... if EXP holds
true.
*
(receive/name loop formals exp form0 ...) SYNTAX
RECEIVE/NAME is a multi-values analogue of named LET (but much less
useful) that helps when chaining n-valued n-ary functions, for instance.
Synopsis: Bind LOOP to a macro wrapped around the procedure LUP with
parameter list FORMALS and body FORM0 ... so that
* (LOOP multi-valued-expression) calls LUP with the values of
multi-valued-expression , and
* (LOOP exp0 ...) becomes (LUP exp0 ...)
Syntax: (receive/name <identifier> <formals> <expression> <body>)
with non-terminals from R5RS.
Semantics: (A special case is good enough.)
Assuming the LOOP tag isn't shadowed in the context `...'
(receive/name loop (x y) exp0
... (loop exp1) ...)
is eqv to
(receive (x y) exp0
(let lup ((x x) (y y))
... (receive (x y) exp1
(lup x y)) ...))
and (receive/name loop (x y) exp0
... (loop exp1 exp1) ...)
is eqv to
(receive (x y) exp0
(let lup ((x x) (y y))
... (lup exp1 exp2) ...))
Example:
(define (shove n xs) (values (- n 1) (cons n xs)))
(receive/name loop (n xs) (values 7 '())
(if (= n 0)
(display xs)
(loop (shove n xs))))
==> (1 2 3 4 5 6 7)
*
(gen-dispatch ((predicate action) ...) e0 e1 ... en) SYNTAX
Dispatch action on type of first argument E0: feed E0 ... EN to the
first action such that the PREDICATE holds for E0. Signal an error
if nothing goes.
Example:
(gen-dispatch ((string? string-ref)
(vector? vector-ref)
(list? list-ref))
'#(a zopp 36) 2)
==> 36
[ Yes, this macro doesn't help much. ]
oOo
a2ea760cb6