How to use library for functions?

[alexec]

How can I convert the "greet" example into a lib please?

This does not work:

import org.projectnessie.cel.EnvOption;
import org.projectnessie.cel.Library;
import org.projectnessie.cel.ProgramOption;
import org.projectnessie.cel.checker.Decls;
import org.projectnessie.cel.interpreter.functions.Overload;

import java.util.List;

import static org.projectnessie.cel.common.types.StringT.stringOf;

public class GreetLib implements Library {
    @Override
    public List<EnvOption> getCompileOptions() {
        return List.of(
                EnvOption.declarations(
                        List.of(
                                Decls.newVar("i", Decls.String),
                                Decls.newVar("you", Decls.String),
                                Decls.newFunction(
                                        "greet",
                                        Decls.newInstanceOverload(
                                                "string_greet_string", List.of(Decls.String, Decls.String), Decls.String)))
                )
        );
    }

    @Override
    public List<ProgramOption> getProgramOptions() {
        return List.of(
                ProgramOption.functions(
                        Overload.binary(
                                "string_greet_string",
                                (lhs, rhs) ->
                                        stringOf(String.format("Hello %s! Nice to meet you, I'm %s.\n", rhs,
                                                lhs))))

        );
    }
}

    @Test
    void merge() throws Exception {
        String greeting = ScriptHost
                .newBuilder()
                .build()
                .buildScript("i.greet(you)")
                .withLibraries(new GreetLib())
                .build()
                .execute(String.class, Map.of("i", "alex", "you", "you"));

        assertEquals("hello alex", greeting);
    }

Results in:

org.projectnessie.cel.tools.ScriptExecutionException: no such overload: string.greet[](string)

	at org.projectnessie.cel.tools.Script.evaluate(Script.java:59)
	at org.projectnessie.cel.tools.Script.execute(Script.java:45)
	at com.intuit.pavedroad.apimanagement.exteventingestorapp.rest.services.cel.GreetLibTest.merge(GreetLibTest.java:33)
	

[alexec]

Looks like it might be a bug:

cel-java/tools/src/main/java/org/projectnessie/cel/tools/ScriptHost.java

Line 138 in c966875

List<ProgramOption> programOptions = new ArrayList<>();

Where is the call to getProgramOptions this func should contain?

@snazy thoughts? Is this a bug?

[XN137]

getProgramOptions is used here:

cel-java/core/src/main/java/org/projectnessie/cel/Library.java

Lines 54 to 66 in c966875

	static EnvOption Lib(Library l) {
	return e -> {
	for (EnvOption opt : l.getCompileOptions()) {
	e = opt.apply(e);
	if (e == null) {
	throw new NullPointerException(
	String.format("env option of type '%s' returned null", opt.getClass().getName()));
	}
	}
	e.addProgOpts(l.getProgramOptions());
	return e;
	};
	}

which gets used here in ScriptHost:

cel-java/tools/src/main/java/org/projectnessie/cel/tools/ScriptHost.java

Lines 123 to 125 in c966875

	envOptions.addAll(libraries.stream().map(Library::Lib).collect(Collectors.toList()));
	Env env = newCustomEnv(registry, envOptions);

also note that we have a test for ScriptHost with a custom library here:

cel-java/tools/src/test/java/org/projectnessie/cel/tools/ScriptHostTest.java

Lines 116 to 139 in 5749d57

	@Test
	void library() throws Exception {
	class MyLib implements Library {
	@Override
	public List<EnvOption> getCompileOptions() {
	return Collections.singletonList(
	EnvOption.declarations(
	Decls.newFunction(
	"foo", Decls.newOverload("foo_void", Collections.emptyList(), Decls.Int))));
	}
	@Override
	public List<ProgramOption> getProgramOptions() {
	return Collections.singletonList(
	ProgramOption.functions(Overload.function("foo", e -> IntT.intOf(42))));
	}
	}
	ScriptHost scriptHost = ScriptHost.newBuilder().build();
	Script script = scriptHost.buildScript("foo()").withLibraries(new MyLib()).build();
	assertThat(script.execute(Integer.class, Collections.emptyMap())).isEqualTo(42);
	}

from that example i am guessing you should be using "greet" instead of "string_greet_string" in your getProgramOptions() ?
if not, feel free to extend the testcase with a failing example and possible fix in a PR please