feat(errors): improve error handling and reporting

src/main.lisp

@@ -12,7 +12,9 @@
 ;;; https://lispcookbook.github.io/cl-cookbook/scripting.html#with-sbcl---images-and-executables
 (defun main ()
   "Entry point for Homestead"
+  (format t "Initialising...~%")
   (conf:init)
+  (format t "Building...~%")
   (process-metadata-tree (load-metadata)))
 
 (defun build-full-permalink (permalink &optional parent-permalink)

src/node.lisp

@@ -30,6 +30,6 @@
                         :if-exists :supersede
                         :if-does-not-exist :create)
         (write-sequence output-html stream))
-      (format t "[OK] ~a~%" (a-get node :permalink)))
+      (format t "~a ~a~%" (util:ansi-green "   [OK]") (util:ansi-strong (a-get node :permalink))))
     (error (err)
-      (format t "[ERROR] processing failed: ~a (~a)~%" (a-get node :permalink) err))))
+      (format t "~a ~a:~%~8T~a~%" (util:ansi-red "[ERROR]") (util:ansi-strong (a-get node :permalink)) err))))

src/util.lisp

@@ -5,6 +5,9 @@
     #:join
     #:slurp
     #:merge-plists
+    #:ansi-red
+    #:ansi-green
+    #:ansi-strong
     #:build-path
     #:build-output-path
     #:find-file-path
@@ -19,17 +22,17 @@
 
 (defun slurp (pathname)
   "Reads the entire contents of the file at PATHNAME and returns it as a string.
-   NIL is returned if the file at PATHNAME cannot be accessed."
-  (when pathname
-    (if (probe-file pathname)
-      (with-open-file (stream pathname
-                        :direction :input
-                        :if-does-not-exist nil)
-        (with-output-to-string (out)
-          (loop for line = (read-line stream nil nil)
-            while line do (write-string line out)
-            (write-char #\Newline out))))
-      nil)))
+   An error of the type file-error is signaled if the file at PATHNAME does not
+   exist."
+  (if (probe-file pathname)
+    (with-open-file (stream pathname
+                      :direction :input
+                      :if-does-not-exist :error)
+      (with-output-to-string (out)
+        (loop for line = (read-line stream nil nil)
+          while line do (write-string line out)
+          (write-char #\Newline out))))
+    nil))
 
 (defun merge-plists (p1 p2)
   "Merge two plists, P1 and P2. Values from P2 override values from P1."
@@ -38,6 +41,18 @@
       do (setf (getf result key) value))
     result))
 
+(defun ansi-red (string)
+  "Wrap STRING in ANSI escape codes for red text"
+  (format nil "~c[31m~a~c[0m" #\Esc string #\Esc))
+
+(defun ansi-green (string)
+  "Wrap STRING in ANSI escape codes for green text"
+  (format nil "~c[32m~a~c[0m" #\Esc string #\Esc))
+
+(defun ansi-strong (string)
+  "Wrap STRING in ANSI escape codes for strong text."
+  (format nil "~c[1;37m~a~c[0m" #\Esc string #\Esc))
+
 (defun build-path (permalink &optional (extension "html"))
   "Return path for file with extension EXTENSION representing PERMALINK"
   (let ((permalink (if (string= permalink "/") "index" permalink)))