Eval seems to behave differently in typed and untyped racket

Questions & Answers
1

My problem looks the same as Provide an example using “eval-syntax” & “syntax” in typed/racket, but isn't reading/parsing and type-checking going on at the same time? Or, doesn't this behaviour break the Scheme motto that code is data (or data is code)?

A racket prompt in drracket produces:

> (eval (with-input-from-string
          "(begin
             (define x 234)
             (define y 432))"
          read))
> x
234
> y
432
>

whereas a typed/racket prompt shows this:

> (eval (with-input-from-string
      "(begin
         (: x Integer)
         (define x 2))"
    read))
> x
. Type Checker: missing type for identifier;
 consider adding a type annotation with `:'
  identifier: x in: x
> (begin
         (: z Integer)
         (define z 222))
> z
- : Integer
222

If I create a module and then require it, it works, too:

> (eval (with-input-from-string
    "(module temp typed/racket
    (provide (all-defined-out))
    (begin
      (: x Integer) (define x 6)
      (: y Natural) (define y 7)))"
    read))
> (require 'temp)
> x
- : Integer
6
> y
- : Integer [more precisely: Nonnegative-Integer]
7
1 Like