ui: Add `args-fold*' and use it.

* guix/ui.scm (args-fold*): New procedure.
* guix/scripts/build.scm, guix/scripts/download.scm,
  guix/scripts/gc.scm, guix/scripts/hash.scm, guix/scripts/import.scm,
  guix/scripts/package.scm, guix/scripts/pull.scm,
  guix/scripts/refresh.scm: Use `args-fold*' instead of `args-fold'.

9 files changed, 63 insertions, 49 deletions

diff --git a/guix/scripts/build.scm b/guix/scripts/build.scm
index 0bf154dd41..4464d84dfc 100644
--- a/guix/scripts/build.scm
+++ b/guix/scripts/build.scm
@@ -149,12 +149,12 @@ Build the given PACKAGE-OR-DERIVATION and return their output paths.\n"))
 (define (guix-build . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
   (define (register-root paths root)
     ;; Register ROOT as an indirect GC root for all of PATHS.
diff --git a/guix/scripts/download.scm b/guix/scripts/download.scm
index 220211e6b8..da5fa5be9e 100644
--- a/guix/scripts/download.scm
+++ b/guix/scripts/download.scm
@@ -90,12 +90,12 @@ Supported formats: 'nix-base32' (default), 'base32', and 'base16'
 (define (guix-download . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
   (with-error-handling
     (let* ((opts  (parse-options))
diff --git a/guix/scripts/gc.scm b/guix/scripts/gc.scm
index 7625bc46e6..cecb68ec36 100644
--- a/guix/scripts/gc.scm
+++ b/guix/scripts/gc.scm
@@ -141,12 +141,12 @@ interpreted."
 (define (guix-gc . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
   (define (symlink-target file)
     (let ((s (false-if-exception (lstat file))))
diff --git a/guix/scripts/hash.scm b/guix/scripts/hash.scm
index ad05a4e66f..deded63136 100644
--- a/guix/scripts/hash.scm
+++ b/guix/scripts/hash.scm
@@ -90,13 +90,13 @@ Supported formats: 'nix-base32' (default), 'base32', and 'base16'
 (define (guix-hash . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "unrecognized option: ~a~%")
-                        name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "unrecognized option: ~a~%")
+                         name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
     (let* ((opts (parse-options))
            (args (filter-map (match-lambda
diff --git a/guix/scripts/import.scm b/guix/scripts/import.scm
index 0b95afced1..6f75017d6e 100644
--- a/guix/scripts/import.scm
+++ b/guix/scripts/import.scm
@@ -95,12 +95,12 @@ Import and convert the Nix expression ATTRIBUTE of NIXPKGS.\n"))
 (define (guix-import . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
   (let* ((opts (parse-options))
          (args (filter-map (match-lambda
diff --git a/guix/scripts/package.scm b/guix/scripts/package.scm
index c5656efc14..cea49a57f4 100644
--- a/guix/scripts/package.scm
+++ b/guix/scripts/package.scm
@@ -446,12 +446,12 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
 (define (guix-package . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (leave (_ "~A: extraneous argument~%") arg))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (leave (_ "~A: extraneous argument~%") arg))
+                %default-options))
 
   (define (guile-missing?)
     ;; Return #t if %GUILE-FOR-BUILD is not available yet.
diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm
index f99e8c1e3d..f4135efc99 100644
--- a/guix/scripts/pull.scm
+++ b/guix/scripts/pull.scm
@@ -173,12 +173,12 @@ Download and deploy the latest version of Guix.\n"))
 (define (guix-pull . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (leave (_ "~A: unexpected argument~%") arg))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (leave (_ "~A: unexpected argument~%") arg))
+                %default-options))
 
   (with-error-handling
     (let ((opts  (parse-options))
diff --git a/guix/scripts/refresh.scm b/guix/scripts/refresh.scm
index da318b07ad..6584282f93 100644
--- a/guix/scripts/refresh.scm
+++ b/guix/scripts/refresh.scm
@@ -93,12 +93,12 @@ specified with `--select'.\n"))
 (define (guix-refresh . args)
   (define (parse-options)
     ;; Return the alist of option values.
-    (args-fold args %options
-               (lambda (opt name arg result)
-                 (leave (_ "~A: unrecognized option~%") name))
-               (lambda (arg result)
-                 (alist-cons 'argument arg result))
-               %default-options))
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
 
   (define core-package?
     (let* ((input->package (match-lambda
diff --git a/guix/ui.scm b/guix/ui.scm
index f8826cd488..7a37ad2cee 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -29,6 +29,7 @@
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
+  #:use-module (srfi srfi-37)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (_
@@ -46,6 +47,7 @@
             fill-paragraph
             string->recutils
             package->recutils
+            args-fold*
             run-guix-command
             program-name
             guix-warning-port
@@ -370,6 +372,18 @@ WIDTH columns."
           (and=> (package-description p) description->recutils))
   (newline port))
 
+(define (args-fold* options unrecognized-option-proc operand-proc . seeds)
+  "A wrapper on top of `args-fold' that does proper user-facing error
+reporting."
+  (catch 'misc-error
+    (lambda ()
+      (apply args-fold options unrecognized-option-proc
+             operand-proc seeds))
+    (lambda (key proc msg args . rest)
+      ;; XXX: MSG is not i18n'd.
+      (leave (_ "invalid argument: ~a~%")
+             (apply format #f msg args)))))
+
 (define (show-guix-usage)
   ;; TODO: Dynamically generate a summary of available commands.
   (format (current-error-port)