muScript: bind operator

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/Bind.java

@@ -0,0 +1,37 @@
+package io.gitlab.jfronny.muscript.ast.dynamic;
+
+import io.gitlab.jfronny.muscript.ast.DynamicExpr;
+import io.gitlab.jfronny.muscript.data.Scope;
+import io.gitlab.jfronny.muscript.data.dynamic.DFinal;
+import io.gitlab.jfronny.muscript.data.dynamic.Dynamic;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class Bind extends DynamicExpr {
+    public final DynamicExpr callable;
+    public final DynamicExpr parameter;
+
+    public Bind(int chStart, int chEnd, DynamicExpr callable, DynamicExpr parameter) {
+        super(chStart, chEnd);
+        this.callable = callable;
+        this.parameter = parameter;
+    }
+
+    @Override
+    public Dynamic<?> get(Scope dataRoot) {
+        return DFinal.of(args -> {
+            List<Dynamic<?>> argsWithParameter = new LinkedList<>(args.getValue());
+            argsWithParameter.add(0, parameter.get(dataRoot));
+            return callable.get(dataRoot)
+                    .asCallable()
+                    .getValue()
+                    .apply(DFinal.of(argsWithParameter));
+        });
+    }
+
+    @Override
+    public DynamicExpr optimize() {
+        return new Bind(chStart, chEnd, callable.optimize(), parameter.optimize());
+    }
+}

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/Call.java

@@ -35,8 +35,12 @@ public class Call extends DynamicExpr {
 
     @Override
     public DynamicExpr optimize() {
-        DynamicExpr left = this.left.optimize();
         List<Arg> args = new ArrayList<>();
+        DynamicExpr left = this.left.optimize();
+        if (left instanceof Bind bind) {
+            left = bind.callable;
+            args.add(new Arg(bind.parameter, false));
+        }
         for (Arg arg : this.args) args.add(arg.optimize());
         return new Call(chStart, chEnd, left, args);
     }

muscript/src/main/java/io/gitlab/jfronny/muscript/compiler/Lexer.java

@@ -75,7 +75,7 @@ public class Lexer {
                 }
                 case ',' -> createToken(Token.Comma);
                 case '?' -> createToken(Token.QuestionMark);
-                case ':' -> createToken(Token.Colon);
+                case ':' -> createToken(match(':') ? Token.DoubleColon : Token.Colon);
                 case '(' -> createToken(Token.LeftParen);
                 case ')' -> createToken(Token.RightParen);
                 case '[' -> createToken(Token.LeftBracket);

muscript/src/main/java/io/gitlab/jfronny/muscript/compiler/Parser.java

@@ -232,7 +232,7 @@ public class Parser {
     private Expr<?> call() {
         Expr<?> expr = primary();
 
-        while (match(Token.LeftParen, Token.Dot, Token.LeftBracket)) {
+        while (match(Token.LeftParen, Token.Dot, Token.LeftBracket, Token.DoubleColon)) {
             int start = previous.start;
             int end = previous.current - 1;
             expr = switch (previous.token) {
@@ -241,6 +241,10 @@ public class Parser {
                     TokenData name = consume(Token.Identifier, "Expected field name after '.'.");
                     yield new Get(start, end, asDynamic(expr), Expr.literal(name.start, name.current - 1, name.lexeme));
                 }
+                case DoubleColon -> {
+                    TokenData name = consume(Token.Identifier, "Expected variable name after '::'.");
+                    yield new Bind(start, end, new Variable(name.start, name.current - 1, name.lexeme), expr.asDynamicExpr());
+                }
                 case LeftBracket -> {
                     expr = new Get(start, end, asDynamic(expr), expression());
                     consume(Token.RightBracket, "Expected closing bracket");

muscript/src/main/java/io/gitlab/jfronny/muscript/compiler/Token.java

@@ -29,5 +29,7 @@ public enum Token {
 
     Semicolon,
 
+    DoubleColon,
+
     Error, EOF
 }

muscript/src/test/java/io/gitlab/jfronny/muscript/test/BindTest.java

@@ -0,0 +1,17 @@
+package io.gitlab.jfronny.muscript.test;
+
+import io.gitlab.jfronny.muscript.compiler.Parser;
+import org.junit.jupiter.api.Test;
+
+import static io.gitlab.jfronny.muscript.test.util.MuTestUtil.makeArgs;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class BindTest {
+    @Test
+    void simpleBind() {
+        assertEquals(30, Parser.parseScript("""
+                fn = {n, b -> n*b*2}
+                5::fn(3)
+                """).run(makeArgs()).asNumber().getValue());
+    }
+}