Semantics and Types in Functional Logic Programming

Liberal Typing for Functional Logic Programs

“…-The well-typedness criterion given in this paper provides a valuable alternative to in the management of type-unsoundness problems due to the use of HO-patterns in function definitions. Both works, which are technically compared at the end of Section 3.3, improve largely the solutions given previously in (González-Moreno et al, 2001). As concrete advantages of the proposal in this paper, we can type equality, solving known problems of opaque decomposition (González-Moreno et al, 2001) (Section 5.1) and, most remarkably, we can type the apply function appearing in the HO-to-FO translation used in standard FLP implementations (Section 5.2).…”

“…Both works, which are technically compared at the end of Section 3.3, improve largely the solutions given previously in (González-Moreno et al, 2001). As concrete advantages of the proposal in this paper, we can type equality, solving known problems of opaque decomposition (González-Moreno et al, 2001) (Section 5.1) and, most remarkably, we can type the apply function appearing in the HO-to-FO translation used in standard FLP implementations (Section 5.2). -Finally, we further discuss in Section 6 the strengths and weaknesses of our proposal, and we end up with some conclusions in Section 7.…”

“…This is not an exoticism: it is known (López-Fraguas et al, 2008) that extensionality is not a valid principle within the combination of HO, non-determinism and call-time choice. It is also known that HO-patterns cause some bad interferences with types: (González-Moreno et al, 2001) and considered that problem, and this paper makes also some contributions in this sense.…”

Multi-paradigm Declarative Languages

“…CRWL can be used as the logical foundation of functional logic languages with non-strict nondeterministic operations. It is a basis for the verification of functional logic programs [27] and has been extended in various directions, e.g., higher-order operations [37], algebraic types [17], polymorphic types [35], failure [68], constraints [67] etc. An account on CRWL and its applications can be found in [77].…”

“…Since this might result also in instantiations that are not intended w.r.t. the given types, one can restrict these instantiations to well-typed ones which requires to keep type information at run time [16,35]. Another option is the instantiation of function variables to (well-typed) lambda terms in order to cover programs that can reason about bindings and block structure [55].…”