At Mon, 10 Sep 2012 00:25:29 +0200, Nada Amin wrote:
> Hello,
>
> Redex has been really useful in exploring examples in a calculus we're
> developing. Now, I would like to use Redex's typesetting facility to
> render these examples (to avoid introducing bugs when translating them
> to TeX). For this, it would be great if I could specify that something
> should be rendered as a subscript.
>
> Here is a dummy example just to illustrate what I mean:
> #lang racket
> (require redex)
>
> (define-language dummy
> (e (p natural) (n natural)))
>
> (define (dummy-rewriters thunk)
> (with-compound-rewriters
> (['p (lambda (lws) (list (list-ref lws 2)))]
> ['n (lambda (lws) (list "-" (list-ref lws 2)))])
> (thunk)))
>
> > (dummy-rewriters (lambda () (render-term dummy (p 1))))
> 1
> > (dummy-rewriters (lambda () (render-term dummy (n 1))))
> -1
>
> Let's say, I'd like to render (n 1) as the equivalent of TeX $1_n$. Is
> that possible?
I think you must drop down to the pict-construction layer to do that.
The example below uses `text' with the 'subscript option.
Getting the line, column, and span for a rewriter result can be tricky.
Usually, you want the result of a rewriter to have the same start and
span as the input. I think I got that part right, below, too.
> Incidentally, is there a better way to re-use compound
> rewriters?
No, I usually write a function like your `dummy-rewriters'.
------------------------------------------------------------
#lang racket
(require redex
slideshow/pict)
(define-language dummy
(e (p natural) (n natural)))
(define (collapse a b)
;; Build a zero-width element that takes the same columns
;; as a through b
(build-lw ""
(lw-line a) (+ (- (lw-line b) (lw-line a))
(lw-line-span b))
(lw-column a) (+ (- (lw-column b) (lw-column a))
(lw-column-span b))))
(define (dummy-rewriters thunk)
(with-compound-rewriters
(['n (lambda (lws)
(list (collapse (first lws) (list-ref lws 1))
(list-ref lws 2)
(text (symbol->string (lw-e (list-ref lws 1)))
`(subscript . ,(default-style))
(default-font-size))
(collapse (list-ref lws 3) (last lws))))])
(thunk)))
(dummy-rewriters (lambda () (render-term dummy (n 1))))
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