Swift Sequence Helpers

SequenceHelpers.swift

// These helpers allow for basic operations to be performed while still iterating over a sequence once without
// adding all of the common boilerplate code you'd normally have to write
extension Sequence {
    // filter + forEach
    func forEach(where predicate: (Element) -> Bool, _ body: (Element) throws -> Void) rethrows {
        for element in self where predicate(element) {
            try body(element)
        }
    }
    
    // compactMap + forEach
    func forEach<TransformedElement>(compactMapping: (Element) -> TransformedElement?, _ body: (TransformedElement) throws -> Void) rethrows {
        for element in self {
            guard let transformed = compactMapping(element) else { continue }
            try body(transformed)
        }
    }
}

// Usage (Playground Context):

// Example 1: Use function that takes in argument
func doStuff(_ element: Foo) { /* ... */ }
elements.forEach(where: { $0 < 3 }, doStuff(_:))
// Example 2: Use block as a trailing closure
elements.forEach(where: { $0 < 3 }) {
    doStuff($0) 
}

// Example 3: Use function that takes in argument
elements.forEach(compactMapping: { $0 as? Foo }, doStuff(_:))
// Example 4: Use block as trailing closure
elements.forEach(compactMapping: { $0 as? Foo }) {
    doStuff($0) 
}