Implemented negative numbers

src/build/token/Tokenize.go

@@ -131,7 +131,15 @@ func Tokenize(buffer []byte) List {
 					i++
 				}
 
-				tokens = append(tokens, Token{Kind: Number, Position: position, Length: Length(i - position)})
+				last := len(tokens) - 1
+
+				if len(tokens) > 0 && tokens[last].Kind == Negate {
+					tokens[last].Kind = Number
+					tokens[last].Length = Length(i-position) + 1
+				} else {
+					tokens = append(tokens, Token{Kind: Number, Position: position, Length: Length(i - position)})
+				}
+
 				continue
 			}
 

src/build/token/Tokenize_test.go

@@ -166,6 +166,19 @@ func TestNegateAfterOperator(t *testing.T) {
 	}
 }
 
+func TestNegateNumber(t *testing.T) {
+	tokens := token.Tokenize([]byte(`-1`))
+
+	expected := []token.Kind{
+		token.Number,
+		token.EOF,
+	}
+
+	for i, kind := range expected {
+		assert.Equal(t, tokens[i].Kind, kind)
+	}
+}
+
 func TestOperatorAssign(t *testing.T) {
 	tokens := token.Tokenize([]byte(`a += b -= c *= d /= e &= f |= g ^= h <<= i >>= j`))