I implemented a data processing API for customers to write convert and validate their unstructured tabular data in a defined way. For each column a user could

I implemented a data processing API for customers to write convert and validate their unstructured tabular data in a defined way. For each column a user could specify/override one of 5 functions. cast: (str|null) -> T compute: T -> T validate: (T) -> Message[] // doesn't modify the value serialize: (T) -> str // primarily used so dates can be formatted Each function was guarded by a try/catch block. This allowed users to write simple functions and not have an edge case blow up all of processing. It ended up working pretty well. I don't think it was quite railway oriented programming, more a carefully thought out framework.