revamp evaluable functors, add missing evaluable functors

src/prolog/machine/term_expansion.rs

@@ -3,7 +3,8 @@ use prolog_parser::parser::*;
 
 use prolog::machine::*;
 use prolog::machine::machine_indices::HeapCellValue;
-use prolog::num::*;
+use prolog::rug::Integer;
+use prolog::rug::ops::Pow;
 
 use std::cell::Cell;
 use std::collections::VecDeque;
@@ -306,7 +307,7 @@ impl MachineState {
         // names in the pre-expansion term. This formula ensures that all generated "numbervars"-
         // style variable names will be longer than the keys of the var_dict, and therefore
         // not equal to any of them.
-        printer.numbervars_offset = pow(BigInt::from(10), max_var_length) * 26;
+        printer.numbervars_offset = Integer::from(10).pow(max_var_length as u32) * 26;
         printer.drop_toplevel_spec();
 
         printer.see_all_locs();