On 6/17/19 4:20 PM, Robert Girault wrote:
I was able to do the first half of exercise 1 (see sources at the end
of this message) --- write a macro computing some information at
run-time. The second half is to write the same macro, but computing
some information at compile-time --- I couldn't do this one. I'm
looking for some directions on how to achieve this.
(*) Context
; Syntax -> Syntax
; (define-world* name ...) defines all name ... to stand for a string
(define-syntax (define-world* stx)
(syntax-parse stx
((_ x:id ...)
#'(define-values (x ...) (values (begin 'x "world") ...)))))
(*) Exercise 1
Exercise 1. Modify define-world* so that it binds each given
identifier to its place in the sequence. We start counting at 0 so
that
(define-world* x y z)
binds x to 0, y to 1, and so on.
Hint 1: If you were going to translate this one example by hand, here's
one way to do it:
(define-values (x y z) (values 0 1 2))
Hint 2: Here's another way to do it:
(begin (define x 0) (define y 1) (define z 2))
Why might the first version be "better" than the second version (from a
macro-writer's point of view, at least)?
Ryan
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