Re: The ?PAIRS word

Montesquiou wrote:
Bonjour to all,

In the archive of the group, I found the word "?PAIRS"
as in

: ENDCASE 4 ?PAIRS COMPILE DROP
BEGIN SP@ CSP @ = 0=
WHILE 2 [COMPILE ENDIF REPEAT
CSP ! ; IMMEDIATE

According the FAQ, the ?PAIRS word was FIG-Forth's way of implementing a
small amount of syntax checking.

Is "Number ?PAIRS" similar to ... over <> if (error message) then ...;

More or less, yes. If you can get the fig-FORTH source, it's in Block
40:

: ?ERROR ( BOOLEAN-2 ERROR TYPE-1, WARN FOR TRUE *)
SWAP IF ERROR ELSE DROP ENDIF ;

: ?PAIRS - 13 ?ERROR ; ( VERIFY STACK VALUES ARE PAIRED *)

Andrew.


.

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