FP-TS for Mere Mortals-Enhanced TypeScript Functionality

Example

pipe( array.of(3), array.map(n => n * 3), array.foldLeft(() => 0, (b, a) => b + a) )

Scenario

Used to transform a single value through a series of functions. Ideal for scenarios requiring multiple, successive transformations where readability and maintainability are key. For instance, processing user inputs that need validation, transformation, and then aggregation.

Example

const parseJSON = (json: string): Either<Error, unknown> => try { return right(JSON.parse(json)); } catch (e) { return left(e as Error); }

Scenario

Provides a way to handle errors functionally, allowing for easy error recovery paths without throwing exceptions. Useful in applications like API data fetching where errors need to be managed gracefully.

Example

const User = t.type({ userId: t.number, name: t.string }); const result = User.decode(jsonData); if (isLeft(result)) { console.error('Invalid user data'); } else { console.log('User data is valid'); }

Scenario

Used for runtime type checking and validation of data structures, particularly when consuming external APIs where data integrity is uncertain. It helps in creating robust, fault-tolerant applications that require data validation against a defined schema.