The Forth words are described in this section in the glossary notation that has become a de-facto standard for Forth texts:
word Stack effect wordset pronunciation
--after, where before and after describe the top of stack entries before and after the execution of the word. The rest of the stack is not touched by the word. The top of stack is rightmost, i.e., a stack sequence is written as it is typed in. Note that Gforth uses a separate floating point stack, but a unified stack notation. Also, return stack effects are not shown in stack effect, but in Description. The name of a stack item describes the type and/or the function of the item. See below for a discussion of the types.
All words have two stack effects: A compile-time stack effect and a run-time stack effect. The compile-time stack-effect of most words is – . If the compile-time stack-effect of a word deviates from this standard behaviour, or the word does other unusual things at compile time, both stack effects are shown; otherwise only the run-time stack effect is shown.
Also note that in code templates or examples there can be comments in
parentheses that display the stack picture at this point; there is no
-- in these places, because there is no before-after situation.
gforth-internalas word set.
gforthdescribes words that will work in future releases of Gforth;
gforth-internalwords are more volatile. Environmental query strings are also displayed like words; you can recognize them by the
environmentin the word set field.
The type of a stack item is specified by the character(s) the name starts with: