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

 From: David Van Horn (dvanhorn at ccs.neu.edu) Date: Tue Jul 26 00:20:49 EDT 2011 Previous message: [racket] Sweet expressions; or making it easier to introduce Racket to me and my coworkers :-) Next message: [racket] Sweet expressions; or making it easier to introduce Racket to me and my coworkers :-) Messages sorted by: [date] [thread] [subject] [author]

```On 7/20/11 3:19 PM, Asumu Takikawa wrote:
> On 2011-07-17 19:13:07 +0200, Danny Wilson wrote:
>> Hi List,
>>
>> Short version: is there an implementation of
>> typed/racket or just racket?
>
> I've been curious about sweet expressions myself for a while
> too, so I went ahead and ported David Wheeler's
> implementation for Racket and made it a language you can use
> from planet.
>
> To use, write a #lang line like this:
>
>    #lang asumu/sweet racket
>
>    printf("Hello")

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) }
{ 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))

As a thank you, I opened two tickets on planet. ;)

David

```

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