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; Copyright (c) 1993-2008 by Richard Kelsey. See file COPYING.
; Eval'ing and type-checking code for primitives.
(define-record-type primitive
(id ; for debugging & making tables
arg-predicates ; predicates for checking argument types
eval ; evaluation function
source ; close-compiled source (if any)
expander ; convert call to one using primops
expands-in-place? ; does the expander expand the definition in-line?
inference-rule ; type inference rule
)
())
(define make-primitive primitive-maker)
(define-record-discloser type/primitive
(lambda (primitive)
(list 'primitive (primitive-id primitive))))
(define (eval-primitive primitive args)
(cond ((not (primitive? primitive))
(user-error "error while evaluating: ~A is not a procedure" primitive))
((args-okay? args (primitive-arg-predicates primitive))
(apply (primitive-eval primitive) args))
(else
(user-error "error while evaluating: type error ~A"
(cons (primitive-id primitive) args)))))
; PREDICATES is a (possibly improper) list of predicates that should match
; ARGS.
(define (args-okay? args predicates)
(cond ((atom? predicates)
(if predicates
(every? predicates args)
#t))
((null? args)
#f)
((car predicates)
(and ((car predicates) (car args))
(args-okay? (cdr args) (cdr predicates))))
(else
(args-okay? (cdr args) (cdr predicates)))))
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