packages: Turn 'cache!' into a single-value-return cache.

* guix/packages.scm (cache!): Assume THUNK returns a single value.
(cached): Likewise.
This commit is contained in:
Ludovic Courtès 2017-06-25 16:31:33 +02:00
parent b334674fe5
commit 0b1be8fd57
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@ -870,14 +870,14 @@ (define (cache! cache package system thunk)
SYSTEM."
;; FIXME: This memoization should be associated with the open store, because
;; otherwise it breaks when switching to a different store.
(let ((vals (call-with-values thunk list)))
(let ((result (thunk)))
;; Use `hashq-set!' instead of `hash-set!' because `hash' returns the
;; same value for all structs (as of Guile 2.0.6), and because pointer
;; equality is sufficient in practice.
(hashq-set! cache package
`((,system ,@vals)
`((,system . ,result)
,@(or (hashq-ref cache package) '())))
(apply values vals)))
result))
(define-syntax cached
(syntax-rules (=>)
@ -889,10 +889,8 @@ (define-syntax cached
(match (hashq-ref cache package)
((alist (... ...))
(match (assoc-ref alist key)
((vals (... ...))
(apply values vals))
(#f
(cache! cache package key thunk))))
(#f (cache! cache package key thunk))
(value value)))
(#f
(cache! cache package key thunk)))))
((_ package system body ...)