Effect Schema Patterns

Effect Schema Patterns

Class Instantiation

ALWAYS use Schema.make() for creating instances:

// ✅ GOOD - Use Schema.make()
const user = Schema.make(User)({ name: 'Alice', age: 30 })

// ❌ BAD - Manual construction
const user = { _tag: 'User', name: 'Alice', age: 30 }

Type Guards

ALWAYS use Schema.is() or static .is method:

// ✅ GOOD
if (Standard.is(value)) { ... }
if (Schema.is(Standard)(value)) { ... }

// ❌ BAD - manual _tag check
if (value._tag === 'Standard') { ... }

Enums

ALWAYS inline enum values directly in Schema.Enums():

// ✅ GOOD - inline values, use .enums for runtime access
export const Status = Schema.Enums({
  active: 'active',
  inactive: 'inactive',
})
export type Status = typeof Status.Type
// Runtime: Status.enums.active

// ❌ BAD - separate const object
export const StatusValues = {
  active: 'active',
  inactive: 'inactive',
} as const
export const Status = Schema.Enums(StatusValues)

Key Points

• Use Schema.make() for type-safe instantiation
• Use Schema.is() for type predicates, never manual _tag checks
• Inline enum values directly in Schema.Enums()
• Access runtime enum values via .enums property