utils: Add 'alist?' procedure.

* src/cuirass/utils.scm (alist?): New procedure.
* tests/utils.scm ("alist?"): New test.

src/cuirass/utils.scm

@@ -20,7 +20,9 @@
 
 (define-module (cuirass utils)
   #:use-module (ice-9 match)
+  #:use-module (srfi srfi-1)
   #:export (;; Procedures
+            alist?
             mkdir-p
             make-user-module
             ;; Macros.
@@ -30,6 +32,11 @@
 (define-syntax-rule (λ* formals body ...)
   (lambda* formals body ...))
 
+(define (alist? obj)
+  "Return #t if OBJ is an alist."
+  (and (list? obj)
+       (every pair? obj)))
+
 (define mkdir-p
   (let ((not-slash (char-set-complement (char-set #\/))))
     (λ* (dir #:optional mode)

tests/utils.scm

@@ -25,6 +25,16 @@
 
 (test-begin "utils")
 
+(test-assert "alist?"
+  (and (alist? '())
+       (alist? '(("foo" 1 2)))
+       (alist? '(("foo" . 1)
+                 ("bar" . 2)))
+       (not (alist? 3))
+       (not (alist? '(1 2 3)))
+       (not (alist? 'foo))
+       (not (alist? #:bar))))
+
 (test-assert "with-directory-excursion"
   (let ((old (getcwd))
         (tmp (tmpnam)))