I’ve been remiss in my emacs-fu.  Lexical binding has been around for awhile, but I haven’t played with it. 

Until tonight.

One of the things I discovered is that enabling it isn’t exactly easy when you’re just farting around in an org-mode babel source buffer.  According to the docs you can use set variable lexical-binding to a non-nil value, and you’re golden… with some very annoying caveats: It has to be a buffer-local variable, and it has to be set at the top of the file.  This doesn’t work well in a *scratch* buffer, or an org-mode source buffer for that matter.

Luckily, there is another way.  Eval takes a second argument now, that when true will eval the expression using lexical binding. This makes it really easy to build a macro that is perfect for playing with lexical binding, or using lexical binding in your init file:

(defmacro lexically (&rest forms) 
  "Lexically execute forms"
  `(eval '(progn ,@forms) 
         t))

BAM!  And there you go. Now you can just wrap whatever forms you want in a “lexically” form, and you’re good to go.  This works for random snippets, or full defuns. 

Obviously this isn’t ideal for writing a package, but it is good for smaller snippets in your init file, or messing around.

It’s a small thing, but when I see code like this:

if (somefoo) {
    ....
} // end somefoo

I know I am in for a bad time.  

Don’t do this.  If you do this, stop.  There are plenty of ways to fix this.  One way is by replacing the body of your consequent with a call to a function.  Oh, what’s that? your code depends on 5 variables that are set before the consequent? 

Yea, you’re probably doing that wrong too.

Moose and Squirrel!