You can't 'program in Unix', Unix is an operating system not a programming language. The point of compilers is that you can write code that will run on multiple systems. Grep can use the same 'C' code for MSDOS or UNIX or RT11.

In the words of Kernighan - everyone knows that debugging is harder than coding. Therefore if you are being as clever as you can be when writing the code, you will have no chance of debugging it.