The Transformation Priority Premise

• ({}–>nil) no code at all->code that employs nil
• (nil->constant)
• (constant->constant+) a simple constant to a more complex constant
• (constant->scalar) replacing a constant with a variable or an argument
• (statement->statements) adding more unconditional statements.
• (unconditional->if) splitting the execution path
• (scalar->array)
• (array->container)
• (statement->tail-recursion)
• (if->while)
• (statement->recursion)
• (expression->function) replacing an expression with a function or algorithm
• (variable->assignment) replacing the value of a variable.
• (case) adding a case (or else) to an existing switch or if

Source: http://thecleancoder.blogspot.com/2011/02/fib-t-p-premise.html