diff options
Diffstat (limited to 'gnu/services.scm')
| -rw-r--r-- | gnu/services.scm | 81 |
1 files changed, 69 insertions, 12 deletions
diff --git a/gnu/services.scm b/gnu/services.scm index 9f6e323e18..b1b53fd18b 100644 --- a/gnu/services.scm +++ b/gnu/services.scm @@ -25,6 +25,7 @@ #:use-module (guix profiles) #:use-module (guix sets) #:use-module (guix ui) + #:use-module ((guix utils) #:select (source-properties->location)) #:use-module (guix modules) #:use-module (gnu packages base) #:use-module (gnu packages bash) @@ -47,11 +48,13 @@ service-type-extensions service-type-compose service-type-extend + service-type-default-value service service? service-kind - service-parameters + service-value + service-parameters ;deprecated simple-service modify-services @@ -59,6 +62,9 @@ fold-services service-error? + missing-value-service-error? + missing-value-service-error-type + missing-value-service-error-location missing-target-service-error? missing-target-service-error-service missing-target-service-error-target-type @@ -118,6 +124,10 @@ (target service-extension-target) ;<service-type> (compute service-extension-compute)) ;params -> params +(define &no-default-value + ;; Value used to denote service types that have no associated default value. + '(no default value)) + (define-record-type* <service-type> service-type make-service-type service-type? (name service-type-name) ;symbol (for debugging) @@ -131,7 +141,11 @@ ;; Extend the services' own parameters with the extension composition. (extend service-type-extend ;list of Any -> parameters - (default #f))) + (default #f)) + + ;; Optional default value for instances of this type. + (default-value service-type-default-value ;Any + (default &no-default-value))) (define (write-service-type type port) (format port "#<service-type ~a ~a>" @@ -142,10 +156,56 @@ ;; Services of a given type. (define-record-type <service> - (service type parameters) + (make-service type value) service? (type service-kind) - (parameters service-parameters)) + (value service-value)) + +(define-syntax service + (syntax-rules () + "Return a service instance of TYPE. The service value is VALUE or, if +omitted, TYPE's default value." + ((_ type value) + (make-service type value)) + ((_ type) + (%service-with-default-value (current-source-location) + type)))) + +(define (%service-with-default-value location type) + "Return a instance of service type TYPE with its default value, if any. If +TYPE does not have a default value, an error is raised." + ;; TODO: Currently this is a run-time error but with a little bit macrology + ;; we could turn it into an expansion-time error. + (let ((default (service-type-default-value type))) + (if (eq? default &no-default-value) + (let ((location (source-properties->location location))) + (raise + (condition + (&missing-value-service-error (type type) (location location)) + (&message + (message (format #f (_ "~a: no value specified \ +for service of type '~a'") + (location->string location) + (service-type-name type))))))) + (service type default)))) + +(define-condition-type &service-error &error + service-error?) + +(define-condition-type &missing-value-service-error &service-error + missing-value-service-error? + (type missing-value-service-error-type) + (location missing-value-service-error-location)) + + + +;;; +;;; Helpers. +;;; + +(define service-parameters + ;; Deprecated alias. + service-value) (define (simple-service name target value) "Return a service that extends TARGET with VALUE. This works by creating a @@ -161,7 +221,7 @@ singleton service type NAME, of which the returned service is an instance." service) ((_ svc (kind param => exp ...) clauses ...) (if (eq? (service-kind svc) kind) - (let ((param (service-parameters svc))) + (let ((param (service-value svc))) (service (service-kind svc) (begin exp ...))) (%modify-service svc clauses ...))))) @@ -321,7 +381,7 @@ file." (define* (activation-service->script service) "Return as a monadic value the activation script for SERVICE, a service of ACTIVATION-SCRIPT-TYPE." - (activation-script (service-parameters service))) + (activation-script (service-value service))) (define (activation-script gexps) "Return the system's activation script, which evaluates GEXPS." @@ -432,7 +492,7 @@ and FILE could be \"/usr/bin/env\"." (define (etc-directory service) "Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE." - (files->etc-directory (service-parameters service))) + (files->etc-directory (service-value service))) (define (files->etc-directory files) (file-union "etc" files)) @@ -536,9 +596,6 @@ kernel." ;;; Service folding. ;;; -(define-condition-type &service-error &error - service-error?) - (define-condition-type &missing-target-service-error &service-error missing-target-service-error? (service missing-target-service-error-service) @@ -605,7 +662,7 @@ TARGET-TYPE; return the root service adjusted accordingly." (match (find (matching-extension target) (service-type-extensions (service-kind service))) (($ <service-extension> _ compute) - (compute (service-parameters service)))))) + (compute (service-value service)))))) (match (filter (lambda (service) (eq? (service-kind service) target-type)) @@ -616,7 +673,7 @@ TARGET-TYPE; return the root service adjusted accordingly." (extensions (map (apply-extension sink) dependents)) (extend (service-type-extend (service-kind sink))) (compose (service-type-compose (service-kind sink))) - (params (service-parameters sink))) + (params (service-value sink))) ;; We distinguish COMPOSE and EXTEND because PARAMS typically has a ;; different type than the elements of EXTENSIONS. (if extend |