Compile an anonymous word in a compiled word

Question

I'm currently working on a small interpreter written in Forth. For a small optimization, I'm trying to have a word which creates compiled words. For example, something which behaves like this:

: creator ( -- a )
    :noname ( u -- u )
        10 + ;
;

10 creator execute .
>> 20 ok

I tried several approaches so far and non worked (naïve like above, switching in interpretive mode, trying to compile a string of Forth source). Is this actually possible?

Answer 1

When you write compiling words, you have to be very careful about which words execute at compile time, and which execute at runtime. In this case, 10 + runs at compile time, and will not be compiled into you :noname definition.

I believe this is what you want:

: creator ( -- xt )   :noname ( n1 -- n2 )
   10 postpone literal  postpone +  postpone ; ;

Also note that you may use CREATE DOES> in many cases. E.g. if you want your creator to accept a number which is used by the child word:

: creator ( n1 "name" -- )   create ,
   does> ( n2 -- n1+n2 )   @ + ;