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