The traditionally correct notation for substitutions is (1) e[x - v] xor (2) [v/x]e
The now-common mix of e[x/v] is considered wrong. (Even if I have used it the past or have allowed students to use it.) On Sep 25, 2012, at 3:13 PM, Asumu Takikawa wrote: > Hi all, > > I'm trying to define a Redex lw rewriter that will typeset substitution > nicely, but I'm getting an error that I don't know how to interpret. > I've gotten this before in the past with other rewriters and I've never > been able to figure it out. > > Here is the definition of the rewriter and the error that I get: > > (define (subst-rewriter lws) > (define e (list-ref lws 2)) > (define x (list-ref lws 3)) > (define v (list-ref lws 4)) > (list e "[" v " / " x "]")) > > adjust-spacing: for subst; loc-wrapper takes up too many columns. Expected it > to not pass 17, but it went to 20 > context...: > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:308:4: > loop > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:308:4: > loop > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:308:4: > loop > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:201:4: > ar/e > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:166:2: > apply-rewrites > /home/asumu/plt/racket-git/collects/redex/private/core-layout.rkt:157:2: > lw->pict > /home/asumu/plt/racket-git/collects/redex/private/pict.rkt:144:0 > > /home/asumu/plt/racket-git/collects/redex/private/../../racket/private/map.rkt:26:19: > loop > /home/asumu/plt/racket-git/collects/redex/private/pict.rkt:108:0: > do-reduction-relation->pict > /home/asumu/docs/control-proxy/paper/typesetting.rkt: [running body] > /home/asumu/docs/control-proxy/paper/model.scrbl: [traversing imports] > /home/asumu/docs/control-proxy/paper/control-proxy.scrbl: [traversing > imports] > > /home/asumu/plt/racket-git/collects/scribble/../racket/private/map.rkt:26:19: > loop > /home/asumu/plt/racket-git/collects/scribble/run.rkt: [running body] > > Any idea how I can work around this? > > Cheers, > Asumu > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
