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-rw-r--r--guix/monads.scm4
-rw-r--r--guix/packages.scm9
-rw-r--r--guix/store.scm38
3 files changed, 20 insertions, 31 deletions
diff --git a/guix/monads.scm b/guix/monads.scm
index f97f4add5d..62397dae7c 100644
--- a/guix/monads.scm
+++ b/guix/monads.scm
@@ -67,10 +67,6 @@
;;; "Monadic Programming in Scheme" (see
;;; <http://okmij.org/ftp/Scheme/monad-in-Scheme.html>).
;;;
-;;; The store monad allows us to (1) build sequences of operations in the
-;;; store, and (2) make the store an implicit part of the execution context,
-;;; rather than a parameter of every single function.
-;;;
;;; Code:
;; Record type for monads manipulated at run time.
diff --git a/guix/packages.scm b/guix/packages.scm
index db14f9e0b8..de87681fcd 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -898,7 +898,7 @@ symbolic output name, such as \"out\". Note that this procedure calls
code of derivations to GUILE, a package object."
(lambda (store)
(let ((guile (package-derivation store guile)))
- (%guile-for-build guile))))
+ (values (%guile-for-build guile) store))))
(define* (package-file package
#:optional file
@@ -917,9 +917,10 @@ cross-compilation target triplet."
(let* ((system (or system (%current-system)))
(drv (compute-derivation store package system))
(out (derivation->output-path drv output)))
- (if file
- (string-append out "/" file)
- out))))
+ (values (if file
+ (string-append out "/" file)
+ out)
+ store))))
(define package->derivation
(store-lift package-derivation))
diff --git a/guix/store.scm b/guix/store.scm
index 6fd34bc643..c3a1c57943 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -852,25 +852,15 @@ be used internally by the daemon's build hook."
;;; Store monad.
;;;
-;; return:: a -> StoreM a
-(define-inlinable (store-return value)
- "Return VALUE from a monadic function."
- ;; The monadic value is just this.
- (lambda (store)
- value))
-
-;; >>=:: StoreM a -> (a -> StoreM b) -> StoreM b
-(define-inlinable (store-bind mvalue mproc)
- "Bind MVALUE in MPROC."
- (lambda (store)
- (let* ((value (mvalue store))
- (mresult (mproc value)))
- (mresult store))))
+(define-syntax-rule (define-alias new old)
+ (define-syntax new (identifier-syntax old)))
-;; This is essentially a state monad
-(define-monad %store-monad
- (bind store-bind)
- (return store-return))
+;; The store monad allows us to (1) build sequences of operations in the
+;; store, and (2) make the store an implicit part of the execution context,
+;; rather than a parameter of every single function.
+(define-alias %store-monad %state-monad)
+(define-alias store-return state-return)
+(define-alias store-bind state-bind)
(define (store-lift proc)
"Lift PROC, a procedure whose first argument is a connection to the store,
@@ -878,7 +868,7 @@ in the store monad."
(define result
(lambda args
(lambda (store)
- (apply proc store args))))
+ (values (apply proc store args) store))))
(set-object-property! result 'documentation
(procedure-property proc 'documentation))
@@ -898,7 +888,8 @@ taking the store as its first argument."
"Return as a monadic value the absolute file name in the store of the file
containing TEXT, a string."
(lambda (store)
- (add-text-to-store store name text '())))
+ (values (add-text-to-store store name text '())
+ store)))
(define* (interned-file file #:optional name
#:key (recursive? #t))
@@ -909,8 +900,9 @@ When RECURSIVE? is true, the contents of FILE are added recursively; if FILE
designates a flat file and RECURSIVE? is true, its contents are added, and its
permission bits are kept."
(lambda (store)
- (add-to-store store (or name (basename file))
- recursive? "sha256" file)))
+ (values (add-to-store store (or name (basename file))
+ recursive? "sha256" file)
+ store)))
(define %guile-for-build
;; The derivation of the Guile to be used within the build environment,
@@ -925,7 +917,7 @@ permission bits are kept."
connection."
(parameterize ((%guile-for-build guile-for-build)
(%current-system system))
- (mval store)))
+ (run-with-state mval store)))
;;;