On Mon, Aug 2, 2010 at 9:37 AM, Shriram Krishnamurthi <s...@cs.brown.edu> wrote: > Here is a sequence of steps to do something that seems extremely > simple. I want to create a binary tree of T. > > First, I have no idea what this documentation means: > > (struct:n (t ...)) > is the type of structures named n with field types t. > > All of "struct", "n" and "t" are italicized, suggesting they're all > meta-variables. But only "n" and "t" are explained in the document. > Perhaps "struct:" is meant literally?
This documentation is written confusingly, I'll fix that. > The next few things I do fail miserably, until I get this far: > > (define-struct: (T) Node ([v : T] [l : (BinTreeof t)] [r : (BinTreeof t)])) > (define-type (BinTreeof t) > (U 'empty > [Node t])) > > Now we get a classic impenetrable error message: > > Type Checker: Structure type constructor Node applied to non-regular > arguments (Error) in: (Node t) > > Whatever that means. I rename the two "t"'s in Node to "T"'s: > > (define-struct: (T) Node ([v : T] [l : (BinTreeof t)] [r : (BinTreeof t)])) > (define-type (BinTreeof t) > (U 'empty > [Node t])) This is the same code as above. Did you mean something different? -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
