dhall

Evaluate a Dhall expression

$ dhall <<< "[expression]"

$ dhall < [config.dhall]

$ dhall-to-json <<< "[expression]"

$ dhall-to-yaml < [config.dhall]

$ dhall type < [config.dhall]

$ dhall format < [config.dhall]

$ json-to-dhall '[Type]' < [data.json]

dhall [command] [options]

Dhall is a programmable configuration language that guarantees termination. It provides the power of a programming language (functions, types, imports) while ensuring configurations always produce a result without infinite loops.
Dhall expressions can be converted to JSON, YAML, or other formats for consumption by applications. The language features a strong type system that catches configuration errors at evaluation time.
Key features include: remote imports with integrity checking (content-addressed dependencies), a total type system (no runtime errors), and built-in functions for common transformations.

type

Infer and display the type of an expression.

Normalize an expression.

Format Dhall source code.

Improve Dhall expressions.

Show differences between two expressions.

Compute semantic hash of expression.

Add integrity checks to imports.

Binary encoding/decoding.

Provide detailed error explanations.

Use ASCII output instead of Unicode.

Learning curve for those unfamiliar with typed functional programming. Large configurations can be slow to evaluate. Not all tools natively support Dhall; conversion to JSON/YAML adds a build step. Import caching behavior may surprise users.

Dhall was created by Gabriella Gonzalez and first released in 2016. The name comes from a Hindu grain. It was designed to address the limitations of YAML and JSON for complex configurations while avoiding the Turing-completeness issues that make other templating languages unpredictable. The language has gained adoption for Kubernetes configurations and infrastructure-as-code.

jq(1), yq(1), jsonnet(1)