[bug#69343] [PATCH v5 08/10] Give a separate name to a commonly used expression.

[Herman Rimm via Guix-patches via <guix-patches@gnu.org>]

From: Felix Lechner <felix.lechner@lease-up.com>

* gnu/machine/ssh.scm (roll-back-managed-host): Factor out a
  subexpression into new variable parameters.

Change-Id: I8d70684142bea736042d6c9dc8276ea7bdb9c181
---
 gnu/machine/ssh.scm | 48 ++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm
index efe056dab7..eb8dba3120 100644
--- a/gnu/machine/ssh.scm
+++ b/gnu/machine/ssh.scm
@@ -582,31 +582,29 @@ (define (roll-back-managed-host machine)
   (define roll-back-failure
     (condition (&message (message (G_ "could not roll-back machine")))))
 
-  (mlet* %store-monad ((boot-alternatives (machine->boot-alternatives machine))
-                       (_ -> (if (< (length boot-alternatives) 2)
-                                 (raise roll-back-failure)))
-                       (entries -> (map boot-parameters->menu-entry
-                                        (list (second boot-alternatives))))
-                       (locale -> (boot-parameters-locale
-                                   (second boot-alternatives)))
-                       (crypto-dev -> (boot-parameters-store-crypto-devices
-                                       (second boot-alternatives)))
-                       (store-dir -> (boot-parameters-store-directory-prefix
-                                      (second boot-alternatives)))
-                       (old-entries -> (map boot-parameters->menu-entry
-                                            (drop boot-alternatives 2)))
-                       (bootloader -> (operating-system-bootloader
-                                       (machine-operating-system machine)))
-                       (bootcfg (lower-object
-                                 ((bootloader-configuration-file-generator
-                                   (bootloader-configuration-bootloader
-                                    bootloader))
-                                  bootloader entries
-                                  #:locale locale
-                                  #:store-crypto-devices crypto-dev
-                                  #:store-directory-prefix store-dir
-                                  #:old-entries old-entries)))
-                       (remote-result (machine-remote-eval machine remote-exp)))
+  (mlet* %store-monad
+         ((boot-alternatives (machine->boot-alternatives machine))
+          (_ -> (when (< (length boot-alternatives) 2)
+                  (raise roll-back-failure)))
+          (parameters (second boot-alternatives))
+          (entries -> (list (boot-parameters->menu-entry parameters)))
+          (locale -> (boot-parameters-locale parameters))
+          (crypto-dev -> (boot-parameters-store-crypto-devices parameters))
+          (store-dir -> (boot-parameters-store-directory-prefix parameters))
+          (old-entries -> (map boot-parameters->menu-entry
+                               (drop boot-alternatives 2)))
+          (bootloader -> (operating-system-bootloader
+                          (machine-operating-system machine)))
+          (bootcfg (lower-object
+                    ((bootloader-configuration-file-generator
+                      (bootloader-configuration-bootloader
+                       bootloader))
+                     bootloader entries
+                     #:locale locale
+                     #:store-crypto-devices crypto-dev
+                     #:store-directory-prefix store-dir
+                     #:old-entries old-entries)))
+          (remote-result (machine-remote-eval machine remote-exp)))
     (when (eqv? 'error remote-result)
       (raise roll-back-failure))))
 
-- 
2.45.2