title: POSTPONE
status:

 This page proposes a way to clarify one unclear place in ANS Forth.
 It is not a part of ANS Forth.

description:

 It is unclear how the POSTPONEd word behaves in the interpretation state.

 Let us define "state-sensitive semantics" as the steps b.1) and b.2)
 from 3.4 "The Forth text interpreter":

>    1) if interpreting, perform the interpretation semantics
>       of the definition (see 3.4.3.2), and continue at a);
>    2) if compiling, perform the compilation semantics of
>       the definition (see 3.4.3.3), and continue at a).

The mentioned item a) is
>  a) Skip leading spaces and parse a name (see 3.4.1);
but it is not a part of the "state-sensitive semantics".

POSTPONE is allowed to compile either compilation or
state-sensitive semantics of name. Both will work in compilation
state as prescribed by the standard. But standard programs are
not allowed to perform POSTPONEd things in interpretation state.

There is one exception. There are immediate words (such
as '(' "paren") whose behavior does not depend on STATE.
For such words, the state-sensitive semantics is the same
as compilation semantics (and the same as both interpretation
and execution semantics). POSTPONE is not ambiguous for such words.

page-written-by:
 mlg