I think you are confusing "partial application" and "partial evaluation". Though they are conceptually related.
The former is what happens when you apply a function of arity N to M arguments, where M < N. In Haskell the partially applied function is suspended, pending the rest of its arguments. The latter is a way of taking a program and _some_ of its inputs and transforming/compiling/specialising it into a residual program, by "evaluating" as much as possible, given the inputs you have available. An interesting example of partial evaluation is to take an interpreter for a language and a sample source program, and partially evaluate the interpreter with respect to the program. The result is a version of the interpreter which acts effectively as a compiled version of the source program. In Hudak's paper(s), if I remember correctly, they have an interpreter for a functional language (in continuation passing style), which is parameterised by a monitor function. I think they are trying to argue that you can make the system more efficient if you partially evaluate the interpreter with respect to a particular monitor. It is better than running the interpreter directly. The problem is that I think it is hard to scale to a language like Haskell, though there might have been advances that I am not familiar with. Wikipedia has an entry on partial evaluation which is somewhat useful, though you should probably follow the references at the bottom. Cheers, Bernie. > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:haskell-cafe- > [EMAIL PROTECTED] On Behalf Of jim burton > Sent: 21 March 2007 18:47 > To: haskell-cafe@haskell.org > Subject: [Haskell-cafe] Partial Evaluation > > I am reading Hudak's paper Modular Domain Specific Languages and Tools > [1] and am confused by his use of the term `Partial Evaluation'. I > understand it to mean supplying some but not all arguments to a > function, e.g. (+3) but it seems to mean something else too. This is in > the context of optimising performance: > > "We have used existing partial evaluation techniques to do > this...Unfortunately, there does not currently exist a suitable, > easy-to-use partial evaluator for Haskell. Our approach was to convert > the Haskell program to Scheme, partially evaluate the Scheme program, > and then translate back into Haskell." > > What does P.E, mean here? > > Thanks, > > > [1] Available > http://wiki.ittc.ku.edu/lambda/Image:Hudak- > Modular_Domain_Specific_Languages_and_Tools.pdf > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
