As complex hardware architecture is widely adopted in high-performance computing (HPC), average HPC programmers are faced with serious difficulties in programming in a general-purpose language. Thus domain-specific languages (DSLs) are actively studied for HPC as a solution. DSLs are categorised into external DSLs and embedded DSLs. The latter DSLs are easy to develop but its expressiveness and execution performance are drawbacks. This talk present two techniques we are developing. The first one is protean operators, which give DSLs more flexible syntax, and the latter is deep reification, which is a language mechanism for helping DSL developers implement a more efficient DSL. Bytespresso is our prototype system to examine the idea of deep reification in Java. It is a platform of embedded DSLs in which DSL code is offloaded to external hardware for execution after domain-specific translation.