Domain-specific languages (DSLs) have demonstrated their usefulness within many domains such as finance, robotics, and telecommunication. This success has been exemplified by the publication of a wide range of articles regarding specific DSLs and their merits in terms of improved software quality, programmer efficiency, security, etc. However, there is little public information on what happens to these DSLs after they are developed and published. The lack of information makes it difficult for a DSL practitioner or tool creator to identify trends, current practices, and issues within the field. In this paper, we seek to establish the current state of a DSL's life cycle by analysing 30 questionnaire answers from DSL authors on the design and development, launch, evolution, and end of life of their DSL. On this empirical foundation, we make six recommendations to DSL practitioners, scholars, and tool creators on the subjects of user involvement in the design process, DSL evolution, and the end of life of DSLs.

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.

Domain-specific languages seek to provide domain guarantees that eliminate many errors allowed by general-purpose languages. Still, a domain-specific language requires additional quality assurance measures to ensure that specifications behave as intended by the users. However, some domains may have specific quality assurance measures (e.g., proofs, experiments, or case studies) with little tradition of using quality assurance measures customary to software engineering. We investigate the possibility of accommodating such domains by conducting a workshop with 11 prospective users of a domain-specific language named MAL for the pension industry. The workshop emphasised the need for supporting actuaries with new analytical tools for quality assurance and resulted in three designs: quantity monitors let users identify outlier behaviour, fragment debugging lets users debug with limited evaluative power, and debugging spreadsheets let users visualise, analyse, and remodel concrete calculations with an established domain tool. Based on our experiences, we hypothesise that co-design workshops are a viable approach for DSLs in a similar situation.