[racket] Sweet expressions; or making it easier to introduce Racket to me and my coworkers :-)

On Mon, Jul 25, 2011 at 11:20 PM, David Van Horn <dvanhorn at ccs.neu.edu> wrote:
>
> Cute!  Thanks for the cool planet package.  Here's a slightly larger example
> using Redex, adapted from redex/examples/arithmetic.rkt:
>
> #lang planet asumu/sweet racket
> require rename-in(redex [term quote])
>
> define-language lang
>  e n
>    δ1(e)
>    δ2(e e)
>  δ1 √ add1 sub1
>  δ2 + - * /
>  E hole
>    δ1(E)
>    δ2(e E)
>    δ2(E e)
>  n number
>
> define v
>  reduction-relation lang
>    { √(n) --> ,sqrt('n) }
>    { add1(n) --> ,add1('n) }
>    { sub1(n) --> ,sub1('n) }
>    { +(n_1 n_2) --> ,+('n_1 'n_2) }
>    { -(n_1 n_2) --> ,-('n_1 'n_2) }
>    { *(n_1 n_2) --> ,*('n_1 'n_2) }
>    { /(n_1 n_2) --> ,/('n_1 'n_2) }
>
> define -->_v
>  context-closure v lang E
>
> traces -->_v '-(*(√(36) /(1 2)) +(1 2))
>

If only Redex could typeset in this syntax :)