User defined functions

To define functions by an user himself, `def' statement must be used. Syntactical errors are detected in the parsing phase of Asir, and notified with an indication of where Asir found the error. If a function with the same name is already defined (regardless to its arity,) the new definition will override the old one, and the user will be told by a message,

afo() redefined.

on the screen when a flag verbose is set to a non-zero value by ctrl(). Recursive definition, and of course, recursive use of functions are available. A call for an yet undefined function in a function definition is not detected as an error. An error will be detected at execution of the call of that yet undefined function.

def f(X) { 
    if ( !X )
        return 1;
    else 
        return X * f(X-1);
}

def c(N)
{
    A = newvect(N+1); A[0] = B = newvect(1); B[0] = 1;
    for ( K = 1; K <= N; K++ ) {
        A[K] = B = newvect(K+1); B[0] = B[K] = 1;
        for ( P = A[K-1], J = 1; J < K; J++ ) 
            B[J] = P[J-1]+P[J];
        }
    return A;
}

In the second example, c(N) returns a vector, say A, of length N+1. A[I] is a vector of length I+1, and each element is again a vector which contains as its elements.

In the following, the manner of writing Asir programs is exhibited for those who have no experience in writing C programs.

Go to the first, previous, next, last section, table of contents.