I recently took to programming in racket after starting to take a class from Jay McCarthy (twitter: @jeapostrophe). Racket is a scheme-based language constructed specifically with industrial use in mind, which means it is based on some pretty solid theory while also posessing, like perl and php, a package management system (PLaneT), a JIT compiler, and other goodies that make it a great language to use in the real world.
This language, along with perl (given that 'use lambda' is invoked), allows the programmer to insert an acutal unicode lambda instead of the keyword 'lambda'. DrRacket, racket's native IDE, allows you to insert this character by pressing 'CTRL+\' . After looking at this page and others, I found I could do this in vim, too.
I put the following lines in my .vimrc file (this same entry worked in my _vimrc file, for the windows version, as well):
if &termencoding == ""
let &termencoding = &encoding
map! ^\ ^Qu03bb
I inserted the special characters '^\' (CTRL-\) and ^Q (CTRL-Q) by using the normal vim way: in insert mode, type CTRL-V, then whatever control character you need to. For example, I inserted '^\' by typing CTRL-V, CTRL-\. For CTRL-Q, it was trickier. CTRL-Q is usually a specially bound command, so in order to insert it I had to use its octal number ordinal: CTRL-V, 017, were the keys I typed to insert that character.
Now whenever I'm editing a file, I type CTRL-\ and out pops a bonefied lambda!