How do I substitute from a list of strings in VIM?

Question

I am a vim user, and I want to be able to loop over a range of substrings when I am substituting. How can I use some vim magic to go from a set of lines like this:

Answer 1

This is how I'd attempt that macro.

qa          Records macro in buffer a
/foo    Search for the next instance of 'foo'
3s          Change the next three characters
bar         To the word bar
       Back to command mode.
n           Get the next instance of foo
.           Repeat last command
n           Get the next instance of foo
3s          Change next three letters
baz         To the word bar
       Back to command mode.
.           Repeat last command
q           Stop recording.
1000@a      Do a many times.

Any advice on how to do it better is welcome.

thanks, Martin.