fp-ts Quick Reference

Which Type Should I Use?

Is the operation async?
├─ NO: Does it involve errors?
│   ├─ YES → Either<Error, Value>
│   └─ NO: Might value be missing?
│       ├─ YES → Option<Value>
│       └─ NO → Just use the value
└─ YES: Does it involve errors?
    ├─ YES → TaskEither<Error, Value>
    └─ NO: Might value be missing?
        ├─ YES → TaskOption<Value>
        └─ NO → Task<Value>

Common Imports