Formal Aspects of Computing (1995) 7:314-328 9 1995 BCS Formal Aspects of Computing Some Facile Chemistry Lone Leth and Bent Thomsen European Computer-Industry Research Centre, Munich, Germany Keywords: Chemical abstract machines; Structural operational semantics; Func- tional concurrent programming; CML; Facile; Poly/ML; Distribution; Channel management Abstract. In this paper we use the chemical abstract machine (CHAM) frame- work [BeB90, BeB92, Bou94] for discussing various semantics for the Facile programming language [GMP89, GMP90, FAR93] and for formalising (parts of) its implementations. We use these formal descriptions to argue (informally) about implementability and cost of implementation in terms of low level machinery needed to implement the given semantics. We take the Facile language as source for discussion, but the results also apply to several other new languages such as CML [Rep91, BMT92] and Poly/ML [Mat91]. Characteristic for all these languages is that they combine ideas from the 2-calculus and process algebra, such as CCS [Mil80, Mi189], to support high level constructs for programming concurrent, parallel and/or distributed systems. The full version of this extended summary can be found in [LET94]. 1. Introduction The Facile language [GMP89, GMP90, FAR93] is an experimental programming language resulting from a concrete attempt to integrate the typed call-by-value 2-calculus with a process language similar to CCS [Mil80, Mi189]. Conceptually a distributed Facile system consists of a collection of nodes, each supporting the (simulated) concurrent execution of Facile processes. The sequential behaviour of a Facile process is given as a call-by-value 2-calculus extended with primitives for communication and dynamic channel generation. Nodes can also be dynamically created, processes can be activated at specific nodes, and communication over channels may occur between different nodes. Correspondence and offprint requests to : Lone Leth and Bent Thomsen, European Computer-Industry Research Centre, Arabellastr. 17, D-81925 Munich, Germany