In many application domains, FPGAs are now promoted as a way of getting round the restrictions of specific CPU designs on system scalability. However, in the current state-of-the art, programming FPGAs remains essentially a hardware-oriented activity, relying on dedicated hardware description languages such as VHDL or Verilog. Using these languages requires expertise in digital design and in practice this limits the applicability of FPGA-based solutions. This is particulary true for stream-processing applications, in which some processing must be carried out "on the fly" on digital data streams. In this context, the dataflow programming model offers a very effective way to reduce the gap between high-level formulations and low-level implementations. To support this claim, the authors have recently introduced CAPH, a domain specific language, offering a fully-automated compilation path from high-level dataflow descriptions to FPGA configuration for stream-processing applications. This paper is a introduction to the CAPH language, giving its motivations and main design principles and exposing the basic features of its syntax, semantics and compilation. It also points to experimental results showing that, at least for stream-processing applications, the dataflow model of computation, used jointly as a programming model and an execution model, can offer a very effective way to conciliate abstraction and efficiency when programming FPGAs.