added documentation about current state of lisp support

tablizer.pod

@@ -37,6 +37,7 @@ tablizer - Manipulate tabular output of other programs
     Other Flags:
           --completion <shell> Generate the autocompletion script for <shell>
       -f, --config <file>      Configuration file (default: ~/.config/tablizer/config)
+      -l, --load-path <path>   Load path for lisp plugins (expects *.zy files)
       -d, --debug              Enable debugging
       -h, --help               help for tablizer
       -m, --man                Display manual page
@@ -341,6 +342,66 @@ the C<-L> parameter).
 Colorization can be turned off completely either by setting the
 parameter C<-N> or the environment variable B<NO_COLOR> to a true value.
 
+=head1 LISP PLUGINS [experimental]
+
+Tablizer supports plugins written in zygomys lisp. You can supply a
+directory to the C<-l> parameter containing B<*.zy> files or a single
+.zy file containing lisp code.
+
+You can put as much code as you want into the file, but you need to
+add one lips function to a hook at the end.
+
+The following hooks are available:
+
+=over
+
+=item B<filter>
+
+The  filter hook  works  one a  whole  line of  the  input. Your  hook
+function is expected to return true  or false. If you return true, the
+line will be included in the output, otherwise not.
+
+Multiple filter hook functions are supported.
+
+Example:
+    
+    /*
+    Simple filter hook function. Splits the argument by whitespace,
+    fetches the 2nd element, converts it to an int and returns true
+    if it s larger than 5, false otherwise.
+    */
+    (defn uselarge [line]
+      (cond (> (atoi (second (resplit line `\s+`))) 5) true false))
+    
+    /* Register the filter hook */
+    (addhook %filter %uselarge)
+
+=item B<process>
+
+The process hook function gets a table containing the parsed input
+data (see C<lib/common.go:type Tabdata struct>. It is expected to
+return a pair containing a bool to denote if the table has been
+modified, and the [modified] table. The resulting table may have less
+rows than the original and cells may have changed content but the
+number of columns must persist.
+
+=item B<transpose>
+
+not yet implemented.
+
+=item B<append>
+
+not yet implemented.
+
+=back
+
+Beside the existing language features, the following additional lisp
+functions are provided by tablizer:
+
+    (resplit [string, regex]) => list
+    (atoi    [string])        => int
+    (matchre [string, regex]) => bool
+
 =head1 BUGS
 
 In order to report a bug, unexpected behavior, feature requests