gcc -pthread -I/usr/include/guile/2.2   -c -o piiotest.o piiotest.c
gcc   piiotest.o   -o piiotest
/usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: piiotest.o: in function `main':
piiotest.c:(.text+0x137): undefined reference to `scm_with_guile'
/usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../x86_64-pc-linux-gnu/bin/ld: piiotest.c:(.text+0x148): undefined reference to `scm_shell'
collect2: error: ld returned 1 exit status
make: *** [<builtin>: piiotest] Error 1