implementing closures (ch25)

samples/ch25_closures1.lox

@@ -0,0 +1,13 @@
+// this program should print "outer"; without proper closure support, it shows "global".
+
+var x = "global";
+
+fun outer() {
+    var x = "outer";
+    fun inner() {
+        print x;
+    }
+    inner();
+}
+
+outer();

samples/ch25_closures2.lox

@@ -0,0 +1,22 @@
+fun makeClosure() {
+    var local = "local";
+    fun closure() {
+        print local;
+    }
+    return closure;
+}
+
+var closure = makeClosure();
+closure();
+
+fun makeClosure2(value) {
+    fun closure() {
+        print value;
+    }
+    return closure;
+}
+
+var doughnut = makeClosure("doughnut");
+var bagel = makeClosure("bagel");
+doughnut();
+bagel();

samples/ch25_closures3.lox

@@ -0,0 +1,11 @@
+fun outer() {
+    var a = 1;
+    var b = 2;
+    fun middle() {
+        var c = 3;
+        var d = 4;
+        fun inner() {
+            print a + c + b + d;
+        }
+    }
+}

samples/ch25_closures4.lox

@@ -0,0 +1,8 @@
+fun outer() {
+    var x = "outside";
+    fun inner() {
+        print x;
+    }
+    inner();
+}
+outer();

samples/ch25_closures5.lox

@@ -0,0 +1,10 @@
+fun outer() {
+    var x = "outside";
+    fun inner() {
+        print x;
+    }
+    return inner;
+}
+
+var closure = outer();
+closure();

samples/ch25_closures6.lox

@@ -0,0 +1,22 @@
+var globalSet;
+var globalGet;
+
+fun main() {
+    var a = "initial";
+
+    fun set() { 
+        a = "updated"; 
+    }
+
+    fun get() {
+        print a;
+    }
+
+    globalSet = set;
+    globalGet = get;
+}
+
+main();
+
+globalSet();
+globalGet();