b-michalkiewicz/domain-workflow

Human readable workflows with error handling made easy. Express your workflows in explicit form so anyone can understand and/or write them.

domain-workflow

Human readable workflows with error handling made easy.

Express your workflows in explicit form so anyone can understand and/or write them:

type ParseStringToNumberError = {
    message: string;
};

type ParseStringToNumber = (_: string) => Either<ParseStringToNumberError, number>;
type NumberProcessor = (_: number) => number;
type NumberFormatter = (_: number) => string;

type FancyWorkflow = Workflow<[ParseStringToNumber, NumberProcessor, NumberFormatter]>;

• FancyWorkflow is statically validated and it's result will be Either<ParseStringToNumberError, string>.
• If we mess up your stages inputs and outputs or mix sync/async type your workflow will have never type so you cannot do anything with it.

Write the implementation of the stages elsewhere not to scare/bore the business team then run your workflow by:

const fancyWorkflow: FancyWorkflow = [parseStringToNumber, numberProcessor, numberFormatter];
const fancyWorkflowResult = runWorkflow(fancyWorkflow)("42");
// fancyWorkflowResult is type is Either<ParseStringToNumberError, string>

Don't need to worry if the previous step is an async operation or can fail as all of these are handled automatically so you can focus on writing your stages in separation.

Notes

Read this to understand how Either type works.

This library was inspired by Domain Modeling Made Functional and The Pragmatic Programmer (part about Transforming Programming) books.