/* We need to predeclare M if we want F to be able to see it.
 * This is done using 'extern', same as if it had been in a
 * different compilation unit. */
extern M(byte n) byte;

/* Mutually recursive functions */
proc F(byte n) byte:
    if n=0 then 1 else n - M(F(n-1)) fi
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proc M(byte n) byte:
    if n=0 then 0 else n - F(M(n-1)) fi
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/* Show the first 16 values of each */
proc nonrec main() void:
    byte i;

    write("F:");
    for i from 0 upto 15 do write(F(i):2) od;
    writeln();

    write("M:");
    for i from 0 upto 15 do write(M(i):2) od;
    writeln()
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