Trustfall — Engine for Querying (Almost) Everything

Trustfall is a query engine for querying any kind of data source, from APIs and databases to any kind of files on disk — and even AI models.

• Try Trustfall in your browser
• 10min tech talk + demo
• Examples of querying real-world data with Trustfall

Try Trustfall in your browser

The Trustfall Playground supports running queries against public data sources such as:

• the HackerNews REST APIs: https://play.predr.ag/hackernews
• the rustdoc JSON of top Rust crates: https://play.predr.ag/rustdoc

For example, this link shows the results of the HackerNews query: "Which GitHub or Twitter users are commenting on stories about OpenAI?"

In the Playground, Trustfall is configured to run client-side as WASM, performing all aspects of query processing (parsing, compilation, and execution) within the browser. While this demo highlights Trustfall's ability to be embedded within a target application, it is of course able to be used in a more traditional client-server context as well.

10min tech talk + demo

Trustfall was featured in the "How to Query (Almost) Everything" talk talk at the HYTRADBOI 2022 conference.

Demo from the talk showing the execution of the cross-API query: "Which GitHub Actions are used in projects on the front page of HackerNews with >=10 points?"

The demo executes the following query across the HackerNews and GitHub APIs and over the YAML-formatted GitHub repository workflow files:

{
  HackerNewsTop(max: 200) {
    ... on HackerNewsStory {
      hn_score: score @filter(op: ">=", value: ["$min_score"]) @output

      link {
        ... on GitHubRepository {
          repo_url: url @output

          workflows {
            workflow: name @output
            workflow_path: path @output

            jobs {
              job: name @output

              step {
                ... on GitHubActionsImportedStep {
                  step: name @output
                  action: uses @output
                }
              }
            }
          }
        }
      }
    }
  }
}

Instructions for running the demo are available together with the source code in the demo-hytradboi directory: link.

Examples of querying real-world data with Trustfall

• HackerNews APIs, including an overview of the query language and an example of querying REST APIs.
• RSS/Atom feeds, showing how to query structured data like RSS/Atom feeds.
• airport weather data (METAR), showing how to query CSV data from aviation weather reports.

Trustfall also powers the cargo-semver-checks semantic versioning linter. More details on the role Trustfall plays in that use case are available in this blog post.

Using Trustfall over a new data source

The easiest way to plug in a new data source is by implementing the BasicAdapter trait.

Python bindings are available, and are built automatically on every change to the engine; the most recent version may be downloaded here. A getting started guide for Python is forthcoming (tracking issue); in the meantime, the best resource is the Python bindings' test suite.

Directory Registry

• trustfall is a façade crate. This is the preferred way to use Trustfall.
• trustfall_core contains the query engine internals
• trustfall_derive defines macros that simplify plugging in data sources.
• pytrustfall contains Trustfall's Python bindings
• trustfall_wasm is a WASM build of Trustfall
• trustfall_filetests_macros is a procedural macro used to generate test cases defined by files: they ensure that the function under test, when given an input specified by one file, produces an output equivalent to the contents of another file.
• experiments contains various experimental projects such as the Trustfall web playground.

Copyright 2022-present Predrag Gruevski.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

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