ADD: syntaxic sugar for function declaration.

doc/grammar.bnf

@@ -4,7 +4,10 @@ EXPR ::=
 | ident
 | CALL
 | LAMBDA
+| FUNDECL
 CALL ::= opar EXPR EXPR* cpar
 LAMBDA ::= opar rarrow opar PARAMS cpar BODY cpar
 PARAMS ::= ident*
 BODY ::= EXPR*
+FUNDECL ::=
+| opar ident opar ident PARAMS cpar BODY cpar

examples/fundecl.fk

@@ -0,0 +1,3 @@
+($ (f x y) (* x y))
+
+(assert= 42 (f 6 7))

src/Parser.cpp

@@ -59,7 +59,12 @@ namespace fk
         return consume();
       }
 
-    if (type_all({NODE_OPAR, NODE_RARROW}))
+    if (type_all({NODE_OPAR, NODE_IDENT, NODE_OPAR, NODE_IDENT})
+        && m_tokens[m_cursor + 1]->repr() == "$")
+      {
+        return parse_fundecl();
+      }
+    else if (type_all({NODE_OPAR, NODE_RARROW}))
       {
         return parse_lambda();
       }
@@ -134,6 +139,31 @@ namespace fk
     return node;
   }
 
+  std::shared_ptr<Node> Parser::parse_fundecl()
+  {
+    consume(NODE_OPAR);
+    auto dollar = consume(NODE_IDENT);
+
+    consume(NODE_OPAR);
+    auto ident = consume(NODE_IDENT);
+    auto params = parse_params();
+    consume(NODE_CPAR);
+
+    auto body = parse_body();
+    consume(NODE_CPAR);
+
+    auto res = make_node(NODE_CALL);
+    res->add_child(dollar);
+    res->add_child(ident);
+
+    auto lambda = make_node(NODE_LAMBDA);
+    lambda->add_child(params);
+    lambda->add_child(body);
+    res->add_child(lambda);
+
+    return res;
+  }
+
   std::shared_ptr<Node> Parser::make_node(NodeType type)
   {
     return std::make_shared<Node>(type, "", loc());

src/Parser.hpp

@@ -26,6 +26,7 @@ namespace fk
     std::shared_ptr<Node> parse_lambda();
     std::shared_ptr<Node> parse_params();
     std::shared_ptr<Node> parse_body();
+    std::shared_ptr<Node> parse_fundecl();
 
     std::shared_ptr<Node> make_node(NodeType type);
     Loc loc() const;

tests/Parser.cpp

@@ -47,3 +47,10 @@ TEST_CASE_METHOD(ParserTest, "Parser_lambda")
   test_parse("MODULE(LAMBDA(PARAMS(IDENT[x],IDENT[y]),BODY(INT[7])))",
              " (-> (x y) 7) ");
 }
+
+TEST_CASE_METHOD(ParserTest, "Parser_fundecl")
+{
+  test_parse("MODULE(CALL(IDENT[$],IDENT[f],"
+             "LAMBDA(PARAMS(IDENT[x]),BODY(INT[7]))))",
+             " ($ (f x) 7)  ");
+}