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records: Make 'make-syntactic-constructor' available at load/eval/expand.

* guix/records.scm (make-syntactic-constructor): Wrap in 'eval-when'.
version-0.8.3
Ludovic Courtès 7 years ago
parent
commit
954cea3ae6
  1. 190
      guix/records.scm

190
guix/records.scm

@ -42,102 +42,106 @@
(format #f fmt args ...)
form))))
(define* (make-syntactic-constructor type name ctor fields
#:key (thunked '()) (defaults '())
(delayed '()))
"Make the syntactic constructor NAME for TYPE, that calls CTOR, and expects
(eval-when (expand load eval)
;; This procedure is a syntactic helper used by 'define-record-type*', hence
;; 'eval-when'.
(define* (make-syntactic-constructor type name ctor fields
#:key (thunked '()) (defaults '())
(delayed '()))
"Make the syntactic constructor NAME for TYPE, that calls CTOR, and expects
all of FIELDS to be initialized. DEFAULTS is the list of FIELD/DEFAULT-VALUE
tuples, THUNKED is the list of identifiers of thunked fields, and DELAYED is
the list of identifiers of delayed fields."
(with-syntax ((type type)
(name name)
(ctor ctor)
(expected fields)
(defaults defaults))
#`(define-syntax name
(lambda (s)
(define (record-inheritance orig-record field+value)
;; Produce code that returns a record identical to ORIG-RECORD,
;; except that values for the FIELD+VALUE alist prevail.
(define (field-inherited-value f)
(and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
field+value)
car))
;; Make sure there are no unknown field names.
(let* ((fields (map (compose car syntax->datum) field+value))
(unexpected (lset-difference eq? fields 'expected)))
(when (pair? unexpected)
(record-error 'name s "extraneous field initializers ~a"
unexpected)))
#`(make-struct type 0
#,@(map (lambda (field index)
(or (field-inherited-value field)
#`(struct-ref #,orig-record
#,index)))
'expected
(iota (length 'expected)))))
(define (thunked-field? f)
(memq (syntax->datum f) '#,thunked))
(define (delayed-field? f)
(memq (syntax->datum f) '#,delayed))
(define (wrap-field-value f value)
(cond ((thunked-field? f)
#`(lambda () #,value))
((delayed-field? f)
#`(delay #,value))
(else value)))
(define (field-bindings field+value)
;; Return field to value bindings, for use in 'let*' below.
(map (lambda (field+value)
(syntax-case field+value ()
((field value)
#`(field
#,(wrap-field-value #'field #'value)))))
field+value))
(syntax-case s (inherit #,@fields)
((_ (inherit orig-record) (field value) (... ...))
#`(let* #,(field-bindings #'((field value) (... ...)))
#,(record-inheritance #'orig-record
#'((field value) (... ...)))))
((_ (field value) (... ...))
(let ((fields (map syntax->datum #'(field (... ...))))
(dflt (map (match-lambda
((f v)
(list (syntax->datum f) v)))
#'defaults)))
(define (field-value f)
(or (and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
#'((field value) (... ...)))
car)
(let ((value
(car (assoc-ref dflt (syntax->datum f)))))
(wrap-field-value f value))))
(let ((fields (append fields (map car dflt))))
(cond ((lset= eq? fields 'expected)
#`(let* #,(field-bindings
#'((field value) (... ...)))
(ctor #,@(map field-value 'expected))))
((pair? (lset-difference eq? fields 'expected))
(record-error 'name s
"extraneous field initializers ~a"
(lset-difference eq? fields
'expected)))
(else
(record-error 'name s
"missing field initializers ~a"
(lset-difference eq? 'expected
fields))))))))))))
(with-syntax ((type type)
(name name)
(ctor ctor)
(expected fields)
(defaults defaults))
#`(define-syntax name
(lambda (s)
(define (record-inheritance orig-record field+value)
;; Produce code that returns a record identical to ORIG-RECORD,
;; except that values for the FIELD+VALUE alist prevail.
(define (field-inherited-value f)
(and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
field+value)
car))
;; Make sure there are no unknown field names.
(let* ((fields (map (compose car syntax->datum) field+value))
(unexpected (lset-difference eq? fields 'expected)))
(when (pair? unexpected)
(record-error 'name s "extraneous field initializers ~a"
unexpected)))
#`(make-struct type 0
#,@(map (lambda (field index)
(or (field-inherited-value field)
#`(struct-ref #,orig-record
#,index)))
'expected
(iota (length 'expected)))))
(define (thunked-field? f)
(memq (syntax->datum f) '#,thunked))
(define (delayed-field? f)
(memq (syntax->datum f) '#,delayed))
(define (wrap-field-value f value)
(cond ((thunked-field? f)
#`(lambda () #,value))
((delayed-field? f)
#`(delay #,value))
(else value)))
(define (field-bindings field+value)
;; Return field to value bindings, for use in 'let*' below.
(map (lambda (field+value)
(syntax-case field+value ()
((field value)
#`(field
#,(wrap-field-value #'field #'value)))))
field+value))
(syntax-case s (inherit #,@fields)
((_ (inherit orig-record) (field value) (... ...))
#`(let* #,(field-bindings #'((field value) (... ...)))
#,(record-inheritance #'orig-record
#'((field value) (... ...)))))
((_ (field value) (... ...))
(let ((fields (map syntax->datum #'(field (... ...))))
(dflt (map (match-lambda
((f v)
(list (syntax->datum f) v)))
#'defaults)))
(define (field-value f)
(or (and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
#'((field value) (... ...)))
car)
(let ((value
(car (assoc-ref dflt (syntax->datum f)))))
(wrap-field-value f value))))
(let ((fields (append fields (map car dflt))))
(cond ((lset= eq? fields 'expected)
#`(let* #,(field-bindings
#'((field value) (... ...)))
(ctor #,@(map field-value 'expected))))
((pair? (lset-difference eq? fields 'expected))
(record-error 'name s
"extraneous field initializers ~a"
(lset-difference eq? fields
'expected)))
(else
(record-error 'name s
"missing field initializers ~a"
(lset-difference eq? 'expected
fields)))))))))))))
(define-syntax define-record-type*
(lambda (s)

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