sec 5: implementing fusion

introduce the Cunctation type of delayed arrays
sec 5: fusion/representing producers

the Alloy type, why we separate the two concerns
sec 5: producer/producer fusion
preamble wibbles
use a \code{} macro instead of just \texttt{}
delete the very old stuff
sec 5: ramble on embedding producers
sec 5: mention 'compute'
sec 5: producer/consumer fusion
sec 5: put the two fusion phases together
sec 5: binder elimination
sec-5 wibbles