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?
After several tries, I figure out no, it doesn't. Okay, now I know
the basic syntax.
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]))
Now everything is fine...?!? TR uses cpp to inline aliases?
Shriram
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