Huge improvements to the app/playlist program

04 parameters.arc

@@ -16,7 +16,8 @@
 
 (mac parameterize (parms . body)
   `(%no:#%parameterize ,(pair %.ac-all.parms)
-          ,@%.ac-all.body))
+            ;; TODO: function for this pattern...?
+          ,@(%.ac-all %.nilify.body)))
 
 (mac make-w/ (x)
   `(mac ,(sym:string "w/" x) (v . body)

05 paths.arc

@@ -81,8 +81,8 @@
 
 (def todir (x)
   (zap string x)
-          ;; TODO: last
-  (if (is (x:- len.x 1) #\/)
+      ;; TODO: last
+  (if (or empty.x (is (x:- len.x 1) #\/))
       x
       (string x "/")))
 

06 import.arc

@@ -4,11 +4,11 @@
 ;(load:string %.exec-dir "lib/04 namespaces.arc")
 
 
-(parameter debug? t)
+(parameter debug? nil)
 
 (redef debug args
   (when debug?
-    (apply prn (intersperse " " args))))
+    (apply prn args))) ;(intersperse " " )
 
 
 (parameter import-dirs     (list cwd
@@ -47,8 +47,8 @@
     (fn (path name)
       (let path abspath.path
         (if import-cache.path
-            (debug " skipping:" name)
-            (do (debug " loading: " name)
+            (debug " skipping: " name)
+            (do (debug " loading:  " name)
                 (= import-cache.path t)
                 (w/import-loading t load.path)))))))
 

app/playlist/README.md

@@ -27,8 +27,10 @@ It will then store those .xspf playlists in the "Playlists" folder.
 The S-expression Playlist Format
 ================================
 
-All playlists are composed of two or more S-expressions. The only required
-S-expressions are `title` and `playlist`:
+All playlists are composed of one or more S-expressions. The only required
+S-expression is `title`. The playlist can then optionally include files via
+either the `include` or `playlist` expressions. Here's an example of a simple
+playlist:
 
     (title "foo")
 
@@ -58,16 +60,17 @@ There are three error conditions:
  3. If a pattern does not match any file, an error will be raised.
 
 
-To create a playlist, simply create a new file in the "Templates" folder and
-place the two required S-expressions inside the file: that's it! Now just run
-the program as specified in "How to run".
+To create a playlist, simply create a new file in the "Templates" folder,
+place a `title` expression inside the file, then add an `include` or
+`playlist` expression (or both): that's it! Now just run the program as
+specified in "How to run".
 
 
 Including other playlists
 =========================
 
 If you wish to combine multiple different playlists into a single one, you can
-use the `include` S-expression:
+use the `include` S-expression at the top level:
 
     (include "bar"
              "qux")
@@ -76,6 +79,35 @@ The above will find the playlists "bar" and "qux" and include them into the
 current playlist. If any of the included playlists do not exist, a warning
 will be displayed.
 
+It is also possible to *selectively* include only parts of another playlist by
+using the `w/playlist` form:
+
+    (playlist
+      (w/playlist "foo"
+        "qux"
+        "corge")
+
+      (w/playlist "bar"
+        "nou"
+        "yes"))
+
+The above will include the files "qux" and "corge" from the "foo" playlist, in
+addition to the "nou" and "yes" files from the "bar" playlist. Just like
+normal file matching, you can use sub-strings when adding files from a
+playlist.
+
+One caveat when including files from another playlist: the program will always
+correctly include files regardless of what order the templates are loaded in.
+But the program can't handle infinite loops:
+
+    (title "foo")
+    (include "bar")
+
+    (title "bar")
+    (include "foo")
+
+The above two playlists will cause the program to never terminate.
+
 
 Limiting the scope of a pattern
 ===============================
@@ -100,6 +132,7 @@ S-expression, you can use the `w/folder` S-expression:
         "foo"
         "bar"
         "qux")
+
       (w/folder "other/path/to"
         "foo"
         "bar"