We report on some recent experiments with SML embedded into the Isabelle/Isar theory and proof language, such that the program text may again refer to formal logical entities via antiquotations. The meaning of our antiquotations within SML text observe the different logical environments at compile time, link time (of theory interpretations), and runtime (within proof procedures). As a general design principle we neither touch the logical foundations of Isabelle, nor the SML language implementation. Thus we achieve a modular composition of the programming language and the logic within the Isabelle/Isar framework. Our work should be understood as a continuation and elaboration of the original “LCF system approach”, which has introduced ML as a programming language for theorem proving in the first place.