DMN FEEL: arithmetic negation of function leads to null result -------------------------------------------------------------- Key: DROOLS-5981 URL: https://issues.redhat.com/browse/DROOLS-5981 Project: Drools Issue Type: Bug Components: dmn engine Affects Versions: 7.47.0.Final Reporter: Anton Tieleman Assignee: Matteo Mortari Priority: Minor Attachments: ExpressionTest1.dmn, ExpressionTest2.dmn I noticed that a negated expression like {{-sum( 1, 2, 3 )}} leads to a null result on evaluation. According to section 10.3.1.2 (page 111-113) of the [DMN 1.2 specification document|https://www.omg.org/spec/DMN/1.2/PDF] on item 26 "arithmetic negation" it should be possible to prefix a dash to a FEEL function. However, when evaluated, this makes the expression return null. The non-prefixed version as well as 0-expression works as expected. This is quite a low priority since there is an easy workaround (prefix 0). I observed this behaviour when running an extensive set of tests to validate conversion from a custom expression language in a client's product to DMN FEEL. I have adjusted the conversion using the workaround.