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authorLudovic Courtès <ludo@gnu.org>2017-03-16 13:41:51 +0100
committerLudovic Courtès <ludo@gnu.org>2017-03-16 22:50:15 +0100
commit146db52a188b871769d9512867aa7f409f37dbac (patch)
treeda18d84a0409ba057e1ce3febb3e6407b7288592
parent34d60c49cbffcee2bdaec32f0bfe2fef1c1ea8e6 (diff)
downloadguix-146db52a188b871769d9512867aa7f409f37dbac.tar
guix-146db52a188b871769d9512867aa7f409f37dbac.tar.gz
memoization: Micro-optimize code produced by 'define-cache-procedure'.
* guix/memoization.scm (%nothing): Remove. (define-cache-procedure): Make '%nothing' a local variable, with a literal list.
-rw-r--r--guix/memoization.scm21
1 files changed, 10 insertions, 11 deletions
diff --git a/guix/memoization.scm b/guix/memoization.scm
index d64f60fe9c..5cae283610 100644
--- a/guix/memoization.scm
+++ b/guix/memoization.scm
@@ -31,9 +31,6 @@
(define-syntax-rule (return/1 value)
value)
-(define %nothing ;nothingness
- (list 'this 'is 'nothing))
-
(define-syntax define-cache-procedure
(syntax-rules ()
"Define a procedure NAME that implements a cache using HASH-REF and
@@ -41,15 +38,17 @@ HASH-SET!. Use CALL to invoke the thunk and RETURN to return its value; CALL
and RETURN are used to distinguish between multiple-value and single-value
returns."
((_ name hash-ref hash-set! call return)
- (define (name cache key thunk)
- "Cache the result of THUNK under KEY in CACHE, or return the
+ (define name
+ (let ((%nothing '(this is nothing)))
+ (lambda (cache key thunk)
+ "Cache the result of THUNK under KEY in CACHE, or return the
already-cached result."
- (let ((results (hash-ref cache key %nothing)))
- (if (eq? results %nothing)
- (let ((results (call thunk)))
- (hash-set! cache key results)
- (return results))
- (return results)))))
+ (let ((results (hash-ref cache key %nothing)))
+ (if (eq? results %nothing)
+ (let ((results (call thunk)))
+ (hash-set! cache key results)
+ (return results))
+ (return results)))))))
((_ name hash-ref hash-set!)
(define-cache-procedure name hash-ref hash-set!
call/mv return/mv))))