[plt-scheme] PLAI mzscheme and drscheme question

DrScheme is case-sensitive by default, mzscheme is case-insensitive by
default.

To run PLAI in mzscheme, turn case-sensitivity on, with 'mzscheme -g'

On Wed, 2005-04-06 at 08:43 +0000, Rohan Nicholls wrote:
>   For list-related administrative tasks:
>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> 
> Hi all,
> 
> I am not sure if this is the right place to ask questions about plai,
> if not let me know.  First off, great book I am really enjoying it,
> even if I am sweating some of the stuff in there.:-)
> 
> I have run into a problem where code that drscheme is happy with,
> breaks in mzscheme.  I have attached the whole page of code below, but
> the problem area seems to be this:
> 
> (define-type FunDef
>   [fundef (fun-name symbol?)
>           (arg-name symbol?)
>           (body F1WAE?)])
> 
> 
> When I run code that uses this is:
> 
> (print "{double {double 5}}")
> (interp (parse '{double {double 5}})
>         (list (fundef 'double
>                       'n
>                       (add (id 'n) (id 'n)))))
> 
> >"{double {double 5}}"
> > STDIN::6857: fundef: illegal use of syntax in: (fundef (quote
> double) (quote n) (add (id (quote n)) (id (quote n)))) 
> 
> Maybe it is something I am doing wrong, but if so I can't work out why
> drscheme would be happy with it.
> 
> Here is the code that causes the error (various tests, and other
> comments removed).
> 
> 
> Thanks for any help with this, and if I am going to be asked why I am
> not using drscheme I can post a mail detailing things that make
> drscheme hard to use, but here did not seem the place.
> 
> rohan 
> _________________________________________________________________________
> 
> 
> (require (lib "plai-advanced.ss" "plai" ))
> 
> ;; Just to clarify for my muddled mind.  What is below is not the
> ;; function definition but the use of the function definition.
> ;; ie. our language's equivalent of apply
> (define-type F1WAE
>   [num (n number?)]
>   [add (lhs F1WAE?)(rhs F1WAE?)]
>   [sub (lhs F1WAE?)(rhs F1WAE?)]
>   [with (name symbol?) (named-expr F1WAE?) (body F1WAE?)]
>   [id (name symbol?)]
>   [app (fun-name symbol?) (arg F1WAE?)])
> 
> (define-type FunDef
>   [fundef (fun-name symbol?)
>           (arg-name symbol?)
>           (body F1WAE?)])
> 
> ;; newest form of parse, with apply added in.
> (define parse
>   (lambda (sexp)
>   (cond
>    [(number? sexp) (num sexp)]
>    [(symbol? sexp) (id sexp)]
>    [(list? sexp)
>     (case (first sexp)
>       [(+)(add (parse (second sexp))
>                (parse (third sexp)))]
>       [(-) (sub (parse (second sexp))
>                 (parse (third sexp)))]
>       [(with) (with (first (second sexp))
>                     (parse (second (second sexp)))
>                     (parse (third sexp)))]
>       [else (app (first sexp)
>                   (parse (second sexp)))]
>        )])))
> 
> 
> ;; interp: F1WAE listof(fundef) -> number
> ;; evaluates F1WAE expressions by reducing them to their corresponding values
> (define interp
>   (lambda (expr fundefs)
>     (type-case F1WAE expr
>                [num (n) n]
>                [add (l r) (+ (interp l fundefs) (interp r fundefs))]
>                [sub (l r) (- (interp l fundefs) (interp r fundefs))]
>                [with (bound-id named-expr bound-body)
>                      (interp (subst bound-body
>                                   bound-id
>                                   (num (interp named-expr fundefs)))
>                              fundefs)]
>                [id (v) (error 'interp "Free identifier")]
>                [app (fun-name arg-expr)
>                     (local ([define the-fun-def (lookup-fundef fun-name fundefs)])
>                            (interp (subst (fundef-body the-fun-def)
>                                           (fundef-arg-name the-fun-def)
>                                           (num (interp arg-expr fundefs)))
>                                    fundefs))])))
> ;; helper functions
> (define lookup-fundef
>   (lambda (fun-name fundefs)
>     (cond
>       [(empty? fundefs)
>        (error 'lookup-fundef "Function does not exist")]
>       [else (if (symbol=? fun-name (fundef-fun-name (first fundefs)))
>                 (first fundefs)
>                 (lookup-fundef fun-name (rest fundefs)))])))
> 
> (define subst
>   (lambda (expr sub-id val)
>     (type-case F1WAE expr
>                [num (n) expr]
>                [add (l r) (add (subst l sub-id val)
>                                (subst r sub-id val))]
>                [sub (l r) (sub (subst l sub-id val)
>                                (subst r sub-id val))]
>                [with (bound-id named-expr bound-body)
>                      (if (symbol=? bound-id sub-id)
>                          (with bound-id
>                                (subst named-expr sub-id val)
>                                bound-body)
>                          (with bound-id
>                                (subst named-expr sub-id val) ;; added to take care of scope
>                                (subst bound-body sub-id val)))]
>                [id (v)(if (symbol=? v sub-id) val expr)]
>                [app (fun-name arg-expr)
>                     (app fun-name (subst arg-expr sub-id val))])))
> 
> ;; test
> (print "{double {double 5}}")
> (interp (parse '{double {double 5}})
>         (list (fundef 'double
>                       'n
>                       (add (id 'n) (id 'n)))))
> 
> ;; this yields this error in mzscheme
> ;; > STDIN::6857: fundef: illegal use of syntax in: (fundef (quote
> ;; double) (quote n) (add (id (quote n)) (id (quote n)))) 
> 
> ___________________________________________________________________________________
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