Thanks to the organisers of ICFP 2012, and to Malcolm Wallace and his assistants for videoing and posting talks rapidly. For me, the emergent theme was the rise of DSLs. Kunle Olukotun's keynote (video above) argued that DSLs are reaching maturity as a technology for programming parallel and heterogeneous hardware (although less was said on the equally important question of distributed systems). Lee Pike et al's Experience report: a do-it-yourself high-assurance compiler presented a case study of a real-life DSL used for monitoring safety on aircraft, and a series of techniques to implement DSL's at low cost while increasing confidence that the implementation is correct, and another whole session was devoted to techniques for implementing DSELs (1 2 3). Olivira and Cook's Functional programming with structured graphs applies PHOAS to representing cyclic structures. Nothing to do with DSL's, below is a link to the video of my talk, Propositions as Sessions.