Yes, but I think the library should be combined with struct, which is why I am asking.
On Apr 14, 2010, at 6:23 PM, Robby Findler wrote: > This is probably obvious but you could write a pretty simple function > to build the prefab struct out of the sexp and even put it in a > library to be used as a replacement for read. > > Robby > > On Wednesday, April 14, 2010, Eli Barzilay <[email protected]> wrote: >> On Apr 14, Matthias Felleisen wrote: >>> A lot of libraries read in file content as lists (or S-expressions) >>> of list-based structures (see csv on planet for one example, which I >>> am currently incorporating to a small degree into >>> 2htdp/batch-io). If I had this structure -- including in teaching >>> languages -- I could easily 'view' these S-expressions/lists as >>> structs, making for much more readable code. >> >> +1 for the use case (but I don't have an opinion on whether it >> justifies implementing them or not). And here is how you do it in CL: >> >> Plain list -- with the default keyworded constructor >> >> CL-USER(1): (defstruct (foo (:type list)) x y) >> FOO >> CL-USER(2): (make-foo :y 2 :x 1) >> (1 2) >> CL-USER(3): (foo-x (list 1 2)) >> 1 >> >> >> Tagged list, with a positional constructor with arguments in reverse >> >> CL-USER(4): (defstruct (foo (:type list) :named (:constructor mkfoo (y x))) >> x y) >> FOO >> CL-USER(5): (mkfoo 2 1) >> (FOO 1 2) >> CL-USER(6): (foo-p '(1 2)) ; ("-p" is a bad spelling for "?") >> NIL >> CL-USER(7): (foo-p '(foo 1 2)) >> T >> CL-USER(8): (foo-x (mkfoo 2 1)) >> 1 >> >> >> -- >> ((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay: >> http://barzilay.org/ Maze is Life! >> _________________________________________________ >> For list-related administrative tasks: >> http://list.cs.brown.edu/mailman/listinfo/plt-dev >> _________________________________________________ For list-related administrative tasks: http://list.cs.brown.edu/mailman/listinfo/plt-dev
