ADD: if core function.

FIX: block scope.

examples/fun.gri

@@ -12,3 +12,7 @@
 ;; syntaxic sugar for function declaration
 ($ (c n) (* 2 n))
 (assert-eq? 18 (c 9))
+
+;; inner variable
+($ (d x) ($ y 3) (+ x y))
+(assert-eq? 7 (d 4))

examples/if.gri

@@ -0,0 +1,11 @@
+(assert-eq? 7 (if true 7 9))
+(assert-eq? 9 (if false 7 9))
+
+($ (max x y)
+   (if (> x y)
+       x
+       y
+))
+
+(assert-eq? 32 (max 3 32))
+(assert-eq? 329 (max 329 32))

lib/core.cpp

@@ -4,6 +4,28 @@
 
 GRINO_ERROR(assertion_error);
 
+extern "C" void lib_flow_control(grino::Loader& loader)
+{
+  loader.add_static("if", [](auto& compiler, auto node, auto& prog, auto& sym) {
+    auto cond_node = node->child(1).lock();
+    auto then_node = node->child(2).lock();
+    auto else_node = node->child(3).lock();
+
+    compiler.compile(cond_node, prog, sym);
+    size_t brf = prog.size();
+    prog.push_instr(grino::OPCODE_BRF, 0);
+
+    compiler.compile(then_node, prog, sym);
+    size_t br = prog.size();
+    prog.push_instr(grino::OPCODE_BR, 0);
+
+    prog.set_param(brf, prog.size());
+    compiler.compile(else_node, prog, sym);
+
+    prog.set_param(br, prog.size());
+  });
+}
+
 extern "C" void lib_int(grino::Loader& loader)
 {
   loader.add_native("+", [](auto args){
@@ -306,6 +328,7 @@ extern "C" void lib(grino::Loader& loader)
   lib_int(loader);
   lib_cmp(loader);
   lib_bool(loader);
+  lib_flow_control(loader);
 
   loader.add_native("dump", [](auto args){
     std::string sep;

src/Compiler.cpp

@@ -30,7 +30,6 @@ namespace grino
           }
       } break;
 
-      case NODE_BLOCK:
       case NODE_BODY: {
         for (size_t i=0; i<node->size(); i++)
           {
@@ -43,6 +42,26 @@ namespace grino
           }
           } break;
 
+      case NODE_BLOCK: {
+        enter_scope();
+
+        for (size_t i=0; i<node->size(); i++)
+          {
+            compile(node->child(i).lock(), program, sym);
+
+            if (i < node->size() - 1)
+              {
+                program.push_instr(OPCODE_POP);
+              }
+          }
+                std::cout << "-------------------------" << std::endl;
+        std::cout << sym.string() << std::endl;
+
+        leave_scope();
+        sym.purge(m_scope.size());
+
+      } break;
+
       case NODE_FUNCALL: {
         std::string ident = node->child(0).lock()->repr();