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 [id] exp) SYNTAX
The usual ASSERT macro with an optional ID tag: Signal an error and
complain if EXP evaluates to false. The error message contains the
value of ID (if supplied) and the expression EXP. [ ASSERT being a
macro, we can change it to the trivial form that doesn't evaluate its
arguments and recompile before selling our stuff ... ]
*
(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
oOo
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