title: Is there way I could fix this error ? Undefined symbols for architecture x86_64: (gnu-prolog)
body: <p>My program runs fine on swi prolog but when i try run it using gnu-prolog. It does not run successfully. Im getting this error which I have no idea how to fix. </p>
  
  <p>This is my first error</p>
  
  <p>gprolog
  [myprojectname]</p>
  
  <pre><code>?- ran the program calling the function
  uncaught exception: error(existence_error(procedure,writeln/1),comp/0)
  </code></pre>
  
  <p>I ran it in one line it did not work</p>
  
  <p>i tried to run it in different way on terminal 
  gplc [myprojectname]</p>
  
  <p>gplc [myprojectname]</p>
  
  <pre><code>Undefined symbols for architecture x86_64:
    "predicate(writeln/1)", referenced from:
        predicate(comp/2) in gplcML9Z1g.o
        _Lpred2_1 in gplcML9Z1g.o
        _Lpred2_2 in gplcML9Z1g.o
        _Lpred2_3 in gplcML9Z1g.o
    _Lpred2_4 in gplcML9Z1g.o
  </code></pre>
  
  <p>ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  compilation failed</p>