Align partial application of native functions with jsonata-js (#95) by aeberhart · Pull Request #132 · dashjoin/jsonata-java

aeberhart · 2026-11-05T09:44:22Z

Second of three PRs split out of #130. Builds on #131 (already merged).

Root cause

jsonata-js partially applies a native function by building function($a, $b){ _ } and setting the body to the native function itself (bodyAST.body = native). When the partial is invoked, applyProcedure calls applyNativeFunction, which does not validate the signature. The Java port instead generated a trampoline expression that called the builtin by name ($each($a, $b)). So the signature was checked again, and the function had to be looked up by name.

Changes (following the JS code)

partialApplyNativeFunction sets bodyAST.body = _native (Symbol.body is now Object). Implemented the commented-out applyNativeFunction / getNativeFunctionArguments and the native branch in applyProcedure.
partialApplyProcedure: only ? leaves a parameter unbound. Missing args are bound to null, the way JS binds undefined (incorrect result when $map($, $append(?)) #86).
? comparison: the token value is a Character, so arg.value.equals("?") was always false.
No lookup by name, so custom / unnamed JFunctions with a signature can be partially applied.
Fixed the inverted T1007 check (proc != null vs JS typeof proc === 'undefined').
Arrays now reach $each / $merge through partials such as [5,6] ~> $each(?, …). Those functions iterate arrays like JS for..in since $each / $merge iterate arrays like JS for..in #131 (Incorrect each function signature validation #79).

Notes for reviewers

The arity of a JFunction is taken from its implementing method or its signature. Partially applying custom functions without a signature, Fn* lambdas, and lambdas bound via Frame.bind is left for the third PR (Custom function pipe error #83, together with the JLambda API change). The two Issues-83: Custom function pipe error #85 tests that need it are not included here.
Calling $each([5,6], …) directly is still rejected with T0410, because the signature is still checked on direct calls.
Conflict with Port hot-path optimizations from #102 #129 in the trampoline loop: kept "variable".equals(...) and added the (Symbol) cast for body.

Testing

PartialTest (8 cases): Incorrect each function signature validation #79, incorrect result when $map($, $append(?)) #86, a custom function with a signature, binding of missing args, $merge(?) with arrays, T1007.
OldPrsTest (6 cases): taken from Issues-79: fix each partial invoke #80, Issues-83: Custom function pipe error #85, ISSUES-86: fix arguments checked #87, including the map_in_pipe example.
Full suite: 1769 tests, 0 failures. It also builds with -Dmaven.compiler.release=11.

🤖 Generated with Claude Code

Partially applying a native function now wraps the function itself as the lambda body (bodyAST.body = native) instead of generating a trampoline expression that calls the builtin by name. As in JS, the signature of the native function is not validated when the partial is invoked. - implement applyNativeFunction / getNativeFunctionArguments - only '?' leaves a parameter unbound, missing args are bound to null (#86) - fix '?' comparison (token value is a Character) - no lookup by name, so unnamed / custom JFunctions work (#83) - arity of a JFunctionCallable is taken from its signature - arrays now reach $each / $merge, which iterate them like JS for..in since #131 (#79) - fix inverted T1007 check Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Partial application of custom functions without signature (#85 pipe cases) is left for the follow-up on #83. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

github-actions · 2026-11-05T09:45:30Z

Test Results

1 839 tests +14 1 837 ✅ +14 9s ⏱️ ±0s
126 suites + 2 2 💤 ± 0
126 files + 2 0 ❌ ± 0

Results for commit a1f2a78. ± Comparison against base commit 6bb65b9.

aeberhart · 2026-11-05T09:53:06Z

        for(var ii = 0; ii < expr.arguments.size(); ii++) {
            var arg = expr.arguments.get(ii);
-            if (arg.type.equals("operator") && (arg.value.equals("?"))) {
+            if (arg.type.equals("operator") && (""+arg.value).equals("?")) {


fixes char - string equals which use to be false always

aeberhart · 2026-11-05T09:53:28Z

        // lookup the procedure
        var proc = /* await */ evaluate(expr.procedure, input, environment);
-        if (proc != null && expr.procedure.type.equals("path") && environment.lookup((String)expr.procedure.steps.get(0).value)!=null) {
+        if (proc == null && expr.procedure.type.equals("path") && environment.lookup((String)expr.procedure.steps.get(0).value)!=null) {


original:

// lookup the procedure var proc = await evaluate(expr.procedure, input, environment); if (typeof proc === 'undefined' && expr.procedure.type === 'path' && environment.lookup(expr.procedure.steps[0].value)) {

aeberhart · 2026-11-05T09:54:00Z

        }
-        if (proc.body instanceof Symbol) {
-            result = evaluate(proc.body, proc.input, env);
+        if (proc.body instanceof JFunction) {


moves commented out code from line 1979 on the left

aeberhart · 2026-11-05T09:56:58Z

 //         proc.arguments.forEach(Object (param, index) {
            Object arg = index<args.size() ? args.get(index) : null;
-            if ((arg==null) || (arg instanceof Symbol && ("operator".equals(((Symbol)arg).type) && "?".equals(((Symbol)arg).value)))) {
+            if (arg instanceof Symbol && ("operator".equals(((Symbol)arg).type) && "?".equals(""+((Symbol)arg).value))) {


original:

if (arg && arg.type === 'operator' && arg.value === '?') {

aeberhart · 2026-11-05T09:57:30Z

-        //      return "$" + sigArg;
-        //  }).toList();
-        //  var body = "function(" + String.join(", ", sigArgs) + "){ _ }";
+        var sigArgs = getNativeFunctionArguments(_native);


move commented out code from line 2042 on the left

aeberhart · 2026-11-05T09:58:02Z


        var bodyAST = parser.parse(body);
-        //bodyAST.body = _native;
+        bodyAST.body = _native;


point to parent of this partial fn

aeberhart · 2026-11-05T09:58:22Z

+            if (method != null)
+                return method.getParameterTypes().length;
+            // Java: a JFunctionCallable has no declared parameters, use the signature (if any)
+            return signature != null ? signature.getNumberOfArgs() : 0;


the third part will address this

aeberhart and others added 3 commits November 5, 2026 10:36

Use Collectors.toList() for JDK 11 compatibility

2915021

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Add test cases from #80, #85, #87

a1f2a78

Partial application of custom functions without signature (#85 pipe cases) is left for the follow-up on #83. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

aeberhart requested a review from uw4 November 5, 2026 09:50

aeberhart commented Nov 5, 2026

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Align partial application of native functions with jsonata-js (#95) - #132

Align partial application of native functions with jsonata-js (#95)#132
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aeberhart commented Nov 5, 2026

Root cause

Changes (following the JS code)

Notes for reviewers

Testing

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Test Results

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