3 files changed, 35 insertions, 10 deletions
diff --git a/src/modules/ast/syntax-tree.scm b/src/modules/ast/syntax-tree.scm
index 738b115..b7db8dd 100644
--- a/src/modules/ast/syntax-tree.scm
+++ b/src/modules/ast/syntax-tree.scm
@@ -15,7 +15,16 @@
 
             make-expr
             expr?
-            expr-int
+            expr-type
+
+            make-unary
+            unary?
+            unary-operator
+            unary-expr
+
+            make-const
+            const?
+            const-int
 
             make-id
             id?
@@ -38,9 +47,20 @@
   (expr stmt-expr))
 
 (define-record-type <expr>
-  (make-expr int)
+  (make-expr type)
   expr?
-  (int expr-int))
+  (type expr-type))
+
+(define-record-type <unary>
+  (make-unary op expr)
+  unary?
+  (op unary-operator)
+  (expr unary-expr))
+
+(define-record-type <const>
+  (make-const int)
+  const?
+  (int const-int))
 
 (define-record-type <id>
   (make-id symbol)
diff --git a/src/modules/generator/generator.scm b/src/modules/generator/generator.scm
index 53be252..4a36b92 100644
--- a/src/modules/generator/generator.scm
+++ b/src/modules/generator/generator.scm
@@ -16,7 +16,7 @@
 
 (define (g-expr e)
   ;; for now, we assume only 'return'!
-  (list (make-instruction "movl" (string-append/shared "$" (number->string (expr-int e))) "%eax")
+  (list (make-instruction "movl" (string-append/shared "$" (number->string (const-int (expr-type e)))) "%eax")
         (make-instruction "ret" #f #f)))
 
 (define (g-id i)
diff --git a/src/modules/parser/parser.scm b/src/modules/parser/parser.scm
index ceac389..fa9202d 100644
--- a/src/modules/parser/parser.scm
+++ b/src/modules/parser/parser.scm
@@ -21,12 +21,17 @@
 
 (define (p-stmt tokens)
   (match tokens
-    (`(return ,expr semi-colon)
-     (make-stmt (p-expr (list expr))))
+    (('return expr ... 'semi-colon)
+     (make-stmt (p-expr expr)))
     (_ (die))))
 
 (define (p-expr tokens)
-  (match tokens
-    (((? number? int))
-     (make-expr int))
-    (_ (die))))
+  (make-expr
+   (match tokens
+     (((? integer? int))
+      (make-const int))
+     (((or 'sub 'complement) expr ...)
+      (make-unary (car tokens) (p-expr expr)))
+     (('left-paren expr ... 'right-paren)
+      (p-expr expr))
+     (_ (die)))))