[353] 2024-07-29 13:31:50 kumaym wrote:

requestClarification - compile semantics or compile action of literal word

it's said compile semantics ( x -- ) of literal is to compile the rutime semantics of place x on stack ( -- x ) , in other words the action literal is supposed to do in compilation state is to compile a literal in the definition of currently defining word, and the literal compiled is obtained from the stack at the moment literal is executed (or compiled since it is a immediate word).

so,

: foo [ 4 ] literal ;

is supposed to define a word foo as having 4 in its body, and that's true

see foo
: foo 4 ; ok

following the compilation of foo step by step we first create a word foo then switch to interpretation mode and push 4 to the stack and then go back to compilation mode to compile literal witch being an immediate word gets executed just to compile 4 (what is on the stack) to the definition of foo and then ; ends the definiton, getting a word containing 4 in its body.

But, then shouldn't be equivalent these two definitions?

: foo [ 4 ] literal ;
4 : foo literal ;

so strange they're not, the first one is ok but the last one gives this error in gforth:

*the terminal*:20:17: error: Control structure mismatch
4 : foo literal >>>;<<<
Backtrace:
kernel/cond.fs:114:26                    0 $6FFFFF810200 throw
glocals.fs:635:5                         1 $6FFFFF821AB0 ?struc
kernel/comp.fs:773:5                     2 $6FFFFF806BF0 ;-hook

why?

[r1267] 2024-07-29 17:43:04 ruv replies:

requestClarification - compile semantics or compile action of literal word

shouldn't be equivalent these two definitions?

: foo [ 4 ] literal ;
4 : foo literal ;

They are not equivalent because the word : (colon) leaves colon-sys on the stack, and the word ; (semicolon) consumes this colon-sys from the stack.

Therefore, in the latter case, before the compilation semantics for literal are performed, the top of the stack is ( 4 colon-sys ). See: 3.1.5.1 System-compilation types.

In some Forth systems colon-sys occupies zero items in the data stack. In these systems your two definitions for foo are equivalent. But the latter case is not standard compliant.