[plt-scheme] Novice question: different behavior in def and eval windows

I don't know if this is a bug in Dr. Scheme or a programming
subtlety that escapes me.  Given this definition in the
definitions window,

(define selectors
  (map (λ (a-symbol) (string->symbol (string-append "date-" (symbol->string a-ssymbol))))
       '(year
         month
         day
         week-day
         hour
         minute
         second)))

The expression (map eval selectors) in the evaluations window
gives me a list of procedures, but in the definitions window
gives the error message:

compile: unbound identifier (and no #%top syntax transformer is bound) in: date-year

I am using DrScheme, version 4.2.3, english. 

Thanks,
MJG