[racket] Writing algebraic maths expressions

On Mar 7, 2015, at 7:11 AM, Norman Gray <norman at astro.gla.ac.uk> wrote:

> Another possibility is Sweet expressions, as described at <http://pkg-build.racket-lang.org/doc/sweet/index.html> and <http://readable.sourceforge.net>.  That feels plausible, but (i) the port doesn't seem complete, since when I try:
> 
> #lang sweet-exp racket/base
> 
> let
>  \\
>    a 1
>  *(a a)

> (see <http://sourceforge.net/p/readable/wiki/Scheme-tutorial/>, at 'Grouping and Splitting'), I get 'let: bad syntax (not an identifier and expression for a binding) in: |\\|’.  

For this, sweet-exp uses `group` instead of `\\`.

#lang sweet-exp racket
let
  group
    a 1
    b 2
  {a + b}