1. A method for generating executable code from application source code, comprising: determining a programmatic expression using the application source code; determining a first value for the programmatic expression; compiling the programmatic expression into a first optimized code portion using the first value, an assumption, and an expression scope; executing the application source code; determining that the programmatic expression is modified outside of the expression scope; invalidating the assumption; and de-optimizing the first optimized code portion.