gotmpl4j

A pure-Java implementation of Go's text/template engine, with the Sprig function library and an optional Spring Boot starter. No Go toolchain, no CGo, no native bindings — just the JVM.

It renders the same templates Helm, Hugo, and countless Go CLIs use, and is validated for byte-for-byte parity against Go's own text/template test suite and Sprig's upstream tests.

📖 Documentation: https://www.alexmond.org/gotmpl4j/current/index.html

Modules

Artifact	Description
org.alexmond:gotmpl4j-core	The engine: lexer → parser → AST → executor. Go builtins only; functions are pluggable via ServiceLoader.
org.alexmond:gotmpl4j-sprig	The Sprig function library (strings, lists, dicts, math, crypto, date, semver, encoding, …), auto-discovered when on the classpath.
org.alexmond:gotmpl4j-spring-boot-starter	Spring Boot auto-configuration: a ready-to-inject template engine, configuration properties, a compile cache, function beans, and an optional MVC ViewResolver.

Quick start

<dependency>
    <groupId>org.alexmond</groupId>
    <artifactId>gotmpl4j-sprig</artifactId>
    <version>1.1.0</version>
</dependency>

import org.alexmond.gotmpl4j.GoTemplate;

var tpl = new GoTemplate();                     // auto-loads Sprig from the classpath
tpl.parse("greet", "Hello {{ .name | upper }}!");

var out = new java.io.StringWriter();
tpl.execute("greet", java.util.Map.of("name", "world"), out);
//  -> "Hello WORLD!"

The engine alone (no Sprig) is just gotmpl4j-core; add gotmpl4j-sprig for the Sprig functions, or the starter for Spring Boot integration.

Conformance

Correctness is held to the originals, not to hand-written expectations:

• Engine — ported from Go's text/template exec_test.go tables, rendered through the real Go engine to capture ground-truth output (see .claude/scripts/conformance/).
• Sprig — ported from Masterminds/sprig's own runt/runtv test tables, rendered through the real Sprig funcmap.

The extractor (.claude/scripts/conformance/runtv_extract.go) uses the Go compiler as an oracle: any case whose data isn't portable to the JVM is dropped automatically, and the surviving cases become base64 TSV fixtures asserted by the JUnit conformance suites.

Build

./mvnw clean install      # build + test + format/PMD/checkstyle gates
./mvnw test               # tests only

Requires JDK 17.

License

Apache License 2.0 — see LICENSE.