[Haskell-cafe] Difficulties with tagless - create "primitives" or compose them

[Jacques Carette]

Excellent answer!  Splitting the Symantics class into pieces is one of 
the techniques that we didn't need for solving the original problem 
(tagless partial evaluation without resorting to fancy types) that set 
us on this track. Which is too bad, because it would have made a nice 
addition. The 'typecase pattern', on the other hand, was one of the 
explicit techniques we did use.

One of these days, Oleg, Ken and I need to write a follow-up on this, as 
the code contains a number of extra techniques (in the advanced partial 
evaluation parts) which were not explained in our paper.  And, of 
course, Oleg's added a number of refinements to the general technique 
[see his web site].

I must admit that I find it amusing that most people seem to use 
finally-tagless for writing interpreters, while we created it for 
partial evaluation and program transformation!  [It also allows you to 
do certain kinds of program analyses, but one needs additional 
techniques to make that comfortable - another thing to write up properly].

Jacques