Programmatic Conditional Text

[Daniel Joyce]

Is there some way to do conditional text in Context or Raw tex?

I am writing a coverletter template, and defining custom commands.

Nils Bohr   
Human Resources 
Yoyodyne Inc.
300 Foo Rd,
New Fenwickle, NJ, 55555

        Dear Nihls Bohr:

vs where there is no contact person

Human Resources     
Yoyodyne Inc.
300 Foo Rd,
New Fenwickle, NJ, 5555

        Dear Sir or Madam:

 Is there anyway to test for empty strings, and write stuff like this?

        Daniel Joyce