Welcome to DrRacket, version 8.11 [cs].
Language: racket, with debugging; memory limit: 128 MB.
> (+  3 4)
7
> (define a 7)
> a
7
> +
#<procedure:+>
> 3
3
> 4
4
> a
7
> (foo 3 4)
. . foo: undefined;
 cannot reference an identifier before its definition
> (+ 3 a)
10
> (define factoriall 42)
> factoriall
42
> (lambda (x) x)
#<procedure>
> +
#<procedure:+>
> ((lambda (x) x) 4)
4
> (define id (lambda (x) x))
> if
. if: bad syntax in: if
> id
#<procedure:id>
> (id 3)
3
> lambda
. lambda: bad syntax in: lambda
> +
#<procedure:+>
> (fact 5)
>(fact 5)
> (fact 4)
> >(fact 3)
> > (fact 2)
> > >(fact 1)
< < <1
< < 2
< <6
< 24
<120
120
> (fact-acc 5 1)
>(fact-acc 5 1)
>(fact-acc 4 5)
>(fact-acc 3 20)
>(fact-acc 2 60)
>(fact-acc 1 120)
<120
120
>