Feature/sql by dan323 · Pull Request #46 · dan323/functional-by-annotations

dan323 · 2026-03-23T00:49:17Z

No description provided.

2. Fill CORE_CONCEPTS.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR introduces a new SQL AST + compiler and supporting abstractions in example-functional, alongside a set of list/reader refactors (notably consolidating empty list construction via List.nil() and renaming FunctionFrom → Reader).

Changes:

Add a SQL DSL (SqlAst, Expr) and string compiler (SqlAstCompiler, ExprCompiler) plus Query/RowDecoder and an @Alternative instance (QueryFunctor).
Add infinite-list interleaving via Merged and update zip/lists utilities to use List.nil() consistently.
Rename the function/reader monad implementation to Reader and update usages/tests/docs.

Reviewed changes

Copilot reviewed 43 out of 43 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
sonar-project.properties	Updates SonarQube project key/org settings.
functional-definitions/functional-compiler/src/test/java/com/dan323/functional/util/monad/MonadJoin.java	Removes unused import.
example-functional/src/test/java/com/dan323/functional/StackActionsTest.java	Updates tests to use `List.nil()` for empty stacks.
example-functional/src/test/java/com/dan323/functional/SqlAstCompilerTest.java	Adds test coverage for SQL AST compilation behavior.
example-functional/src/test/java/com/dan323/functional/ReaderTest.java	Updates tests to target `Reader` instead of `FunctionFrom`.
example-functional/src/test/java/com/dan323/functional/ParserTest.java	Updates an empty-list expectation to `List.nil()`.
example-functional/src/test/java/com/dan323/functional/ListZipperTest.java	Uses `List.nil()` for empty zipper construction.
example-functional/src/test/java/com/dan323/functional/ListTest.java	Uses `List.nil()` in length assertion.
example-functional/src/test/java/com/dan323/functional/FiniteListTest.java	Adjusts tests to use `List.nil()` with functional ops.
example-functional/src/test/java/com/dan323/algebraic/FiniteListMonoidTest.java	Adjusts unit expectation to `List.nil()`.
example-functional/src/main/java/module-info.java	Adds `requires java.sql;` for JDBC types used by SQL decoder.
example-functional/src/main/java/com/dan323/functional/data/state/StackActions.java	Switches `FunctionFrom` usage to `Reader` and uses `List.nil()` for reset/print.
example-functional/src/main/java/com/dan323/functional/data/sql/SqlAstCompiler.java	New SQL AST → SQL string compiler with folding/flattening logic.
example-functional/src/main/java/com/dan323/functional/data/sql/SqlAst.java	New sealed SQL AST node definitions.
example-functional/src/main/java/com/dan323/functional/data/sql/RowDecoder.java	New JDBC `ResultSet` row decoding abstraction.
example-functional/src/main/java/com/dan323/functional/data/sql/QueryFunctor.java	New `@Alternative` implementation for SQL queries.
example-functional/src/main/java/com/dan323/functional/data/sql/Query.java	New record tying SQL AST to a `RowDecoder`.
example-functional/src/main/java/com/dan323/functional/data/sql/ExprCompiler.java	New expression-to-SQL compiler.
example-functional/src/main/java/com/dan323/functional/data/sql/Expr.java	New sealed expression AST.
example-functional/src/main/java/com/dan323/functional/data/sql/DbError.java	New error ADT for SQL/decoding.
example-functional/src/main/java/com/dan323/functional/data/sql/Config.java	New example `Reader` usage building a JDBC URL.
example-functional/src/main/java/com/dan323/functional/data/parser/ParserApplicative.java	Uses `List.nil()` for `many` base case.
example-functional/src/main/java/com/dan323/functional/data/list/zipper/ListZipperFunctor.java	Uses `List.nil()` for empty right-side mapping.
example-functional/src/main/java/com/dan323/functional/data/list/zipper/ListZipper.java	Initializes left side with `List.nil()`.
example-functional/src/main/java/com/dan323/functional/data/list/ZipApplicative.java	Refines `liftA2` handling (incl. `Merged` support) and switches nil usage.
example-functional/src/main/java/com/dan323/functional/data/list/Merged.java	New infinite list that interleaves/merges two infinite lists.
example-functional/src/main/java/com/dan323/functional/data/list/ListUtils.java	Refactors concat/reverse to support `List` and `List.nil()`.
example-functional/src/main/java/com/dan323/functional/data/list/List.java	Adds `interleave` and broadens `cycle` to accept `List`.
example-functional/src/main/java/com/dan323/functional/data/list/InfiniteList.java	Updates permitted subclasses to include `Merged`.
example-functional/src/main/java/com/dan323/functional/data/list/FiniteListFunctional.java	Uses `List.nil()` and adapts concat calls.
example-functional/src/main/java/com/dan323/functional/data/list/FiniteList.java	Removes `FiniteList.nil()` in favor of `List.nil()` and updates callers.
example-functional/src/main/java/com/dan323/functional/data/list/Cycle.java	Adjusts empty-check and concat cast after concat refactor.
example-functional/src/main/java/com/dan323/functional/data/function/Reader.java	Renames `FunctionFrom` to `Reader` and updates singleton plumbing.
example-functional/src/main/java/com/dan323/functional/data/continuation/ContinuationMonad.java	Makes `getInstance()` return a singleton instance.
docs/PARSER.md	Updates examples to use `List.nil()`.
docs/FUNCTIONAL_STRUCTURES.md	Updates examples to use `List.nil()`.
docs/EXAMPLES.md	Updates examples to use `List.nil()`.
CLAUDE.md	Adds repository build/test guidance and architecture notes.

Comments suppressed due to low confidence (1)

example-functional/src/test/java/com/dan323/functional/ReaderTest.java:12

Test method names still reference the old FunctionFrom type (e.g. functionFromFunctor) even though the class under test is now Reader. Renaming the test methods to match Reader will keep intent clear and improve searchability.

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Copilot · 2026-03-23T00:54:40Z

+            return c.tableAlias() + "." + c.name();
+        } else if (expr instanceof Expr.Literal<?> l) {
+            if (l.value() instanceof String s) {
+                return "'" + s + "'";


String literals are emitted by simple quoting without escaping embedded single quotes. This produces invalid SQL for values containing ' and can enable SQL injection if any literals originate from user input. At minimum escape single quotes (e.g. replace ' with ''), or preferably compile literals to parameter placeholders and collect parameters separately.

Suggested change

return "'" + s + "'";

String escaped = s.replace("'", "''");

return "'" + escaped + "'";

Copilot · 2026-03-23T00:54:40Z

+        return new Query<>(new SqlAst.Empty(), RowDecoder.empty());
+    }
+
+    public static <A> Query<A> disjunction(Query<A> first, Query<A> snd) {


disjunction unions the SQL ASTs but always keeps first.decoder(). If snd was built with a different decoder (e.g. via map), the union can decode rows incorrectly or fail at runtime. Consider enforcing decoder compatibility (e.g. require equality / same instance) or defining a safe combined decoder strategy.

Suggested change

public static <A> Query<A> disjunction(Query<A> first, Query<A> snd) {

public static <A> Query<A> disjunction(Query<A> first, Query<A> snd) {

if (first.decoder() != snd.decoder()) {

throw new IllegalArgumentException("Cannot create disjunction of queries with different decoders");

}

Copilot · 2026-03-23T00:54:41Z

    public static <A> FiniteList<A> disjunction(FiniteList<A> op1, FiniteList<A> op2) {
-        return ListUtils.concat(op1, op2);
+        return (FiniteList<A>) ListUtils.concat(op1, op2);
    }


disjunction returns (FiniteList<A>) ListUtils.concat(op1, op2), which is an unchecked downcast from List to FiniteList. It would be safer to have ListUtils.concat return FiniteList when both inputs are finite (or add a dedicated FiniteList concat) so callers don’t need casts.

Copilot · 2026-03-23T00:54:41Z

    public static <A, B> FiniteList<B> flatMap(Function<A, FiniteList<B>> f, FiniteList<A> base) {
-        return base.head().maybe(h -> concat(f.apply(h), flatMap(f, base.tail())), FiniteList.nil());
+        return base.head().maybe(h -> (FiniteList<B>) concat(f.apply(h), flatMap(f, base.tail())), List.nil());
    }


flatMap now casts the result of concat(...) back to FiniteList<B>. This is another unchecked cast stemming from concat returning List. Consider tightening concat’s return type for finite inputs (or adding a finite-specific overload) to keep FiniteListFunctional type-safe.

Copilot · 2026-03-23T00:54:41Z

+public record Config(String host, int port, String db) {
+
+    static Function<Config,String> getPath = Reader.<Config>getInstance().liftA2(
+            (url, db) -> url + "/" + db,
+            Reader.<Config>getInstance()
+                    .liftA2((host, port) -> "jdbc:postgresql://" + host + ":" + port, Config::host, Config::port),
+            Config::db);


getPath is declared as a mutable, package-private static field. If this is intended as a stable API constant, make it public static final (or expose it as a method) to prevent accidental reassignment and clarify intended usage.

Copilot · 2026-03-23T00:54:41Z

+    private static Expr.Column<Number> col(String alias, String name) {
+        return new Expr.Column<>(alias, name, Number.class);
+    }
+
+    private static Expr.Column<Integer> colInt(String alias, String name) {
+        return new Expr.Column<>(alias, name, Integer.class);
+    }


The tests (and helpers) build Expr.Column values with a table alias (e.g. "o"/"t"), but SqlAst.Table only carries a table name and SqlAstCompiler never introduces aliases in the rendered FROM/JOIN. This locks in generated SQL like FROM orders WHERE o.amount ... where o is undefined, which won’t execute in SQL engines. Consider extending SqlAst.Table to include an alias (or treating tableAlias as the actual table name) and updating the helpers accordingly so generated SQL declares and consistently uses aliases.

Copilot · 2026-03-23T00:54:41Z

 module functional.data {
    requires functional.annotations;
    requires functional.compiler;
+    requires java.sql;


New public SQL types were added under com.dan323.functional.data.sql, but the module descriptor does not export that package. If these APIs are intended for external use (and tests import them), add exports com.dan323.functional.data.sql; to avoid JPMS accessibility issues for downstream modules.

Copilot · 2026-03-23T00:54:41Z

    public static <A> FiniteList<A> reverse(FiniteList<A> lst) {
-        return lst.head().maybe(h -> concat(reverse(lst.tail()), FiniteList.cons(h, FiniteList.nil())), FiniteList.nil());
+        return lst.head().maybe(h ->(FiniteList<A>) concat(reverse(lst.tail()), FiniteList.cons(h, List.nil())), List.nil());
    }


reverse relies on a forced cast from List to FiniteList. This is only safe if concat(...) is guaranteed to return a FiniteList for finite inputs, but the type system can’t enforce that and a future change could introduce a ClassCastException. Prefer a FiniteList-typed concat overload (e.g. concat(FiniteList, FiniteList)) so reverse stays type-safe.

Copilot · 2026-03-23T00:54:42Z

+    // A fragment can be used directly as a JOIN source only when it has no WHERE
+    // and no custom projection — otherwise it must be wrapped as a subquery.
+    private static String asJoinSource(Fragment fragment) {
+        if (fragment instanceof Fragment.Query q && q.where() == null && "*".equals(q.select())) {
+            return q.from();
+        }
+        return "(" + render(fragment) + ")";
+    }


Subqueries/UNION fragments used as FROM/JOIN sources are wrapped in parentheses but not given a derived-table alias. In PostgreSQL (and many other DBs), FROM (SELECT ...) / FROM ((SELECT ...) UNION ...) requires AS <alias>, and without it column references like t.x are invalid. Add aliasing when wrapping fragments (and ensure expressions reference that alias).

sonarqubecloud · 2026-03-23T01:56:39Z

Quality Gate failed

Failed conditions
75.2% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

dan323 and others added 6 commits March 23, 2026 01:27

1. List overhaul

ebeef78

2. Fill CORE_CONCEPTS.md

sonar

e60e40a

cycled lists

c96a608

Update docs/CORE_CONCEPTS.md

dedeafa

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

cycled lists

6d760b5

Many improvements

9698363

Copilot AI review requested due to automatic review settings March 23, 2026 00:49

Copilot started reviewing on behalf of dan323 March 23, 2026 00:49 View session

Many improvements

9966515

Copilot AI reviewed Mar 23, 2026

View reviewed changes

dan323 added 2 commits March 23, 2026 02:16

Many improvements

e8b2ba7

Many improvements

caa4bda

dan323 merged commit 308173f into master Mar 23, 2026
4 of 5 checks passed

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Feature/sql#46

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	return "'" + s + "'";
	String escaped = s.replace("'", "''");
	return "'" + escaped + "'";

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