Improved test

internal/builder/builder.go

@@ -255,24 +255,7 @@ func (b *Builder) compute(left parser.Value, op parser.Token, right parser.Value
 		return &parser.StringValue{Value: s1 + s2, Quoted: true}
 	}
 
-	lF, lIsF := b.valToFloat(left)
-	rF, rIsF := b.valToFloat(right)
-
-	if lIsF || rIsF {
-		res := 0.0
-		switch op.Type {
-		case parser.TokenPlus:
-			res = lF + rF
-		case parser.TokenMinus:
-			res = lF - rF
-		case parser.TokenStar:
-			res = lF * rF
-		case parser.TokenSlash:
-			res = lF / rF
-		}
-		return &parser.FloatValue{Value: res, Raw: fmt.Sprintf("%g", res)}
-	}
-
+	// Try Integer arithmetic first
 	lI, lIsI := b.valToInt(left)
 	rI, rIsI := b.valToInt(right)
 
@@ -303,6 +286,25 @@ func (b *Builder) compute(left parser.Value, op parser.Token, right parser.Value
 		return &parser.IntValue{Value: res, Raw: fmt.Sprintf("%d", res)}
 	}
 
+	// Fallback to Float arithmetic
+	lF, lIsF := b.valToFloat(left)
+	rF, rIsF := b.valToFloat(right)
+
+	if lIsF || rIsF {
+		res := 0.0
+		switch op.Type {
+		case parser.TokenPlus:
+			res = lF + rF
+		case parser.TokenMinus:
+			res = lF - rF
+		case parser.TokenStar:
+			res = lF * rF
+		case parser.TokenSlash:
+			res = lF / rF
+		}
+		return &parser.FloatValue{Value: res, Raw: fmt.Sprintf("%g", res)}
+	}
+
 	return left
 }
 

internal/parser/parser.go

@@ -319,6 +319,13 @@ func (p *Parser) parseAtom() (Value, bool) {
 			}
 			return val, true
 		}
+		if tok.Value == "!" {
+			val, ok := p.parseAtom()
+			if !ok {
+				return nil, false
+			}
+			return &UnaryExpression{Position: tok.Position, Operator: tok, Right: val}, true
+		}
 		fallthrough
 	case TokenLBrace:
 		arr := &ArrayValue{Position: tok.Position}