---
title: "build_flatMap(_:_:)"
framework: foundation
role: symbol
role_heading: Type Method
path: "foundation/predicateexpressions/build_flatmap(_:_:)-kcbs"
---

# build_flatMap(_:_:)

## Declaration

```swift
static func build_flatMap<LHS, RHS, Wrapped, Result>(_ wrapped: LHS, _ builder: (PredicateExpressions.Variable<Wrapped>) -> RHS) -> PredicateExpressions.OptionalFlatMap<LHS, Wrapped, RHS, Result> where LHS : PredicateExpression, RHS : PredicateExpression, Result == RHS.Output, LHS.Output == Wrapped?
```