We argue that there will be an increasing future need for the design and implementation of declarative languages that can aggregate trust evidence and therefore inform the decision making of IT systems at run-time. We first present requirements for such languages. Then we discuss an instance of such a language, Peal~+, which extends an early prototype Peal that was researched by others in collaboration with us. Next, we formulate the intuitive semantics of Peal~+, present a simple use case of it, and evaluate to what extent Peal~+ meets our formulated requirements. In this evaluation, particular attention is given to the usability aspects of declarative languages that mean to aggregate trust evidence.
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