Constant propagation

[nielstron]

The pluto language is a suitable place to allow for constant propagation where applicable. Concretely

• ITE can be evaluated if the condition is known
• apply(y, x) can be skipped if x has no side effects (i.e. errors or traces) and is discarded in y (concrete use case: constants in opshin are generated by applying the state monad to a function that just returns a constant)
• builtins can be evaluated if all inputs are known

This complements the higher level constant propagation on the opshin/python level and the lower level constant propagation in UPLC which is not aware of patterns.