# Principles - Epsil is [expression-oriented](https://en.wikipedia.org/wiki/Expression-oriented_programming_language): conditionals, matches and blocks produce values. Declarations and effect-oriented loops remain statements. - Errors are values - [Principle of least surprise](https://en.wikipedia.org/wiki/Principle_of_least_astonishment) - defaults represent most common cases - existing conventions and idioms are adopted - [Robustness Principle](https://en.wikipedia.org/wiki/Robustness_principle): be conservative in what you send, liberal in what you accept - Clarity over brevity. - Prefer one idiomatic way to express a concept. - Regularity and Orthogonality. Define a small number of concepts and allow them to be combined without restrictions.