i_add integer addition (+) ck_null ifsT2 S S
subtract subtraction (-) ck_null IfsT2 S S
i_subtract integer subtraction (-) ck_null ifsT2 S S
-concat concatenation (.) or string ck_concat fst2 S S
+concat concatenation (.) or string ck_concat fsT2 S S
stringify string ck_fun fsT@ S
left_shift left bitshift (<<) ck_bitop fsT2 S S