A friend of mine spends a lot time writing programs in R. He often finds himself copy and pasting bits of code. There is often a risk of error in such a process that you might fail to notice parts the code that should be changed from one block to the next. He was hoping for a solution that would allow him to pick out those incorrect bits out more easily.

I came up with a solution that tokenizes source code and then applies the same color highlighting to tokens as they appear throughout a document. It allows you to pick out differences much quicker.

You can find a demo here