Decimal BASIC Open Source Project

Is it possible to call an internal function from an external sub or function?

I tried using DECLARE in the external function but it doesn't work.

The error happens in external sub trymove when I try to execute internal function validmove

DECLARE FUNCTION validmove
DECLARE EXTERNAL SUB trymove
<main program goes here>

FUNCTION validmove(X, Y)
LET validmove = FALSE
IF X<0 OR X>7 OR Y<0 OR Y>7 THEN EXIT FUNCTION
IF Board(X,Y)=FALSE THEN LET validmove = TRUE
END FUNCTION

END

EXTERNAL SUB trymove(X, Y, M, newx, newy)
DECLARE FUNCTION validmove
IF validmove(X, Y) = 0 THEN EXIT SUB
IF validmove(X+1,Y+2) <> 0 THEN LET N = N + 1
IF N>M THEN EXIT SUB
IF N=M AND RND<.5 THEN EXIT SUB
LET M = N
LET newx = X
LET newy = Y
END SUB