# JSONLoader A loader backed by a JSON or JSONL file. ``` struct JSONLoader where Sample : SampleProtocol ``` ## Overview ```swift let url = Bundle.main.url(forResource: "samples", withExtension: "jsonl")! let loader = JSONLoader>(url: url) ``` The format is detected automatically from the file contents: - If the first non-whitespace character is `[`, the file is treated as a JSON array (`[{...}, {...}]`) and decoded in one pass. - Otherwise, the file is treated as JSONL (JSON Lines), where the loader decodes each non-empty line as an individual sample. Malformed entries are logged using `OSLog` and skipped. A failure to open the file propagates as a thrown error. ## Topics ### Initializers [`init(url: URL)`](/documentation/Evaluations/JSONLoader/init(url:)) Creates a loader backed by the JSON or JSONL file at the given URL. ### Instance Properties [`var stream: any AsyncSequence`](/documentation/Evaluations/JSONLoader/stream) The async sequence that reads and yields each sample from the JSON or JSONL file during an evaluation run. ## Relationships ### Conforms To [`Loader`](/documentation/Evaluations/Loader) [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)