Domain-specific languages (DSLs) have emerged as a plausible way for non-programming experts to efficiently express their domain knowledge. Recent DSL research has taken a technical perspective on how and why to create DSLs, resulting in a wealth of innovative tools, frameworks and technical approaches. Less attention has been paid to the design process. Namely, how can it ensure that the created DSL realises the expected benefits? This paper seeks to answer this question when designing DSLs for highly specialised domains subject to resource constraints, an evolving application domain, and scarce user participation. We propose an iteration of alternating activities in a human-centred design method that seeks to minimise the need for expensive implementation and user involvement. The method moves from a low-validity exploration of highly diverse language designs towards a higher-validity exploration of more homogeneous designs. We give an in-depth case study of designing an actuarial DSL called MAL, or Management Action Language, which allows actuaries to model so-called future management actions in asset/liability projections in life insurance and pension companies. The proposed human-centred design method was synthesised from this case study, where we found it useful for iteratively identifying and removing usability problems during the design.

Region-based memory management can be used to control dynamic memory allocations and deallocations safely and efficiently. Existing (direct-style) region systems that statically guarantee region safety---no dereferencing of dangling pointers---are based on refinements of Tofte and Talpin's seminal work on region inference for managing heap memory in stacks of regions.We present a unified Floyd-Hoare Logic inspired region type system for reasoning about and inferring region-based memory management, using a sublanguage of imperative region commands. Our system expresses and performs control-sensitive region management without requiring a stack discipline for allocating and deallocating regions. Furthermore, it captures storage mode analysis and late allocation/early deallocation analysis in a single, expressive, unified logical framework. Explicit region aliasing in combination with reference-counted regions provides flexible, context-sensitive early memory deallocation and simultaneously dispenses with the need for an integrated region alias analysis.In this paper we present the design of our region type system, illustrate its practical expressiveness, compare it to existing region analyses, demonstrate how this eliminates the need for previously required source code rewritings for good memory performance, and describe automatic inference of region commands that give consistently better (or at least equally good) memory performance as existing inference techniques.

AnnoDomini is a source-to-source conversion tool for making COBOL programs Year 2000 compliant. It is technically and conceptually built upon type-theoretic techniques and methods: type-based specification, program analysis by type inference and type-directed transformation. These are combined into an integrated software reengineering tool and method for finding and fixing Year 2000 problems. AnnoDomini's primary goals have been flexibility (support for multiple year representations), completeness (identifying all potential Year 2000 problems), correctness (correct fixes for Year 2000 problems) and a high degree of safe automation in all phases (declarative specification of conversions, no second-guessing or dangerous heuristics).In this paper we present the type-theoretic foundations of AnnoDomini: type system, type inference, unification theory, semantic soundness, and correctness of conversion. We also describe how these foundations have been applied and extended to a common COBOL mainframe dialect, and how AnnoDomini is packaged with graphical user interface and syntax-sensitive editor into a commercially available software tool.