diff --git a/FactGenerator/include/predicates.inc b/FactGenerator/include/predicates.inc
index f4d2e23..6d6eb2e 100644
--- a/FactGenerator/include/predicates.inc
+++ b/FactGenerator/include/predicates.inc
@@ -64,15 +64,18 @@ PREDICATE2(func, param_attr)
 GROUP_END(function)
 
 GROUP_BEGIN(instr)
-PREDICATE(instr, to, instr_assigns_to)
-PREDICATE(instr, flag, instr_flag)
-PREDICATE(instr, next, next_instr)
-PREDICATE(instr, bb_entry, instr_bb_entry)
-PREDICATE(instr, func, instr_func)
-PREDICATE(instr, pos, instr_pos)
-PREDICATE(instr, unreachable, unreachable_instr)
+PREDICATE2(instr, assigns_to)
+PREDICATE2(instr, flag)
+PREDICATE2(instr, successor)
+PREDICATE2(instr, bb_entry)
+PREDICATE2(instr, func)
+PREDICATE2(instr, pos)
 GROUP_END(instr)
 
+GROUP_BEGIN(unreachable)
+PREDICATE2(unreachable, instr)
+GROUP_END(unreachable)
+
 GROUP_BEGIN(add)
 PREDICATE2(add, instr)
 PREDICATEI(add, first_operand)
@@ -187,20 +190,19 @@ GROUP_END(xor_)
 
 GROUP_BEGIN(ret)
 PREDICATE2(ret, instr)
-// TODO(#42):
-PREDICATE(ret, instr_void, void_ret_instr)
-// TODO(#42):
-PREDICATE(ret, operand, ret_instr_value)
+// Can't be named 'void', as that's a C++ keyword.
+PREDICATEI(ret, void_)
+PREDICATEI(ret, operand)
 GROUP_END(ret)
 
 GROUP_BEGIN(br)
 PREDICATE2(br, instr)
-PREDICATE(br, instr_cond, br_cond_instr)
-PREDICATE(br, condition, br_cond_instr_condition)
-PREDICATE(br, cond_iftrue, br_cond_instr_iftrue_label)
-PREDICATE(br, cond_iffalse, br_cond_instr_iffalse_label)
-PREDICATE(br, instr_uncond, br_uncond_instr)
-PREDICATE(br, uncond_dest, br_uncond_instr_dest_label)
+PREDICATEI(br, cond)
+PREDICATEI(br, condition)
+PREDICATEI(br, true_label)
+PREDICATEI(br, false_label)
+PREDICATEI(br, uncond)
+PREDICATEI(br, uncond_label)
 GROUP_END(br)
 
 GROUP_BEGIN(switch_)
diff --git a/FactGenerator/src/FactGenerator.cpp b/FactGenerator/src/FactGenerator.cpp
index 6814cc3..7a5e48b 100644
--- a/FactGenerator/src/FactGenerator.cpp
+++ b/FactGenerator/src/FactGenerator.cpp
@@ -157,7 +157,7 @@ auto FactGenerator::processModule(
         if (!instr.getType()->isVoidTy()) {
           refmode_t targetVar = refmode<llvm::Value>(instr);
 
-          writeFact(pred::instr::to, iref, targetVar);
+          writeFact(pred::instr::assigns_to, iref, targetVar);
           recordVariable(targetVar, instr.getType());
 
           // Save variables for the CPG
@@ -166,7 +166,7 @@ auto FactGenerator::processModule(
         }
 
         // Record successor instruction
-        if (prev_instr) writeFact(pred::instr::next, prev_iref, iref);
+        if (prev_instr) writeFact(pred::instr::successor, prev_iref, iref);
 
         // Store the refmode of this instruction for next iteration
         prev_iref = iref;
diff --git a/FactGenerator/src/InstructionVisitor.cpp b/FactGenerator/src/InstructionVisitor.cpp
index 2c1f459..9d2d9c5 100644
--- a/FactGenerator/src/InstructionVisitor.cpp
+++ b/FactGenerator/src/InstructionVisitor.cpp
@@ -215,7 +215,7 @@ void InstructionVisitor::visitReturnInst(const llvm::ReturnInst &RI) {
   if (RI.getReturnValue()) {  // with returned value
     writeInstrOperand(pred::ret::operand, iref, RI.getReturnValue());
   } else {  // w/o returned value
-    gen.writeFact(pred::ret::instr_void, iref);
+    gen.writeFact(pred::ret::void_, iref);
   }
 }
 
@@ -224,18 +224,18 @@ void InstructionVisitor::visitBranchInst(const llvm::BranchInst &BI) {
 
   if (BI.isConditional()) {  // conditional branch
     // br i1 <cond>, label <iftrue>, label <iffalse>
-    gen.writeFact(pred::br::instr_cond, iref);
+    gen.writeFact(pred::br::cond, iref);
 
     // Condition Operand
     writeInstrOperand(pred::br::condition, iref, BI.getCondition());
 
     // 'iftrue' and 'iffalse' labels
-    writeInstrOperand(pred::br::cond_iftrue, iref, BI.getOperand(1));
-    writeInstrOperand(pred::br::cond_iffalse, iref, BI.getOperand(2));
+    writeInstrOperand(pred::br::true_label, iref, BI.getOperand(1));
+    writeInstrOperand(pred::br::false_label, iref, BI.getOperand(2));
   } else {  // unconditional branch
     // br label <dest>
-    gen.writeFact(pred::br::instr_uncond, iref);
-    writeInstrOperand(pred::br::uncond_dest, iref, BI.getOperand(0));
+    gen.writeFact(pred::br::uncond, iref);
+    writeInstrOperand(pred::br::uncond_label, iref, BI.getOperand(0));
   }
 }
 
@@ -320,7 +320,7 @@ void InstructionVisitor::visitResumeInst(const llvm::ResumeInst &RI) {
 }
 
 void InstructionVisitor::visitUnreachableInst(const llvm::UnreachableInst &I) {
-  recordInstruction(pred::instr::unreachable, I);
+  recordInstruction(pred::unreachable::instr, I);
 }
 
 void InstructionVisitor::visitAllocaInst(const llvm::AllocaInst &AI) {
diff --git a/datalog/export/debug-output-extended.dl b/datalog/export/debug-output-extended.dl
index e11e6fd..e945d9a 100644
--- a/datalog/export/debug-output-extended.dl
+++ b/datalog/export/debug-output-extended.dl
@@ -143,13 +143,13 @@
 .output block_predecessors (compress=true)
 .output boolean_type (compress=true)
 .output boolean_vector_type (compress=true)
-.output br_cond_instr (compress=true)
-.output br_cond_instr_condition (compress=true)
-.output br_cond_instr_iffalse_label (compress=true)
-.output br_cond_instr_iftrue_label (compress=true)
+.output br_instr_cond (compress=true)
+.output br_instr_condition (compress=true)
+.output br_instr_false_label (compress=true)
+.output br_instr_true_label (compress=true)
 .output br_instr (compress=true)
-.output br_uncond_instr (compress=true)
-.output br_uncond_instr_dest_label (compress=true)
+.output br_instr_uncond (compress=true)
+.output br_instr_uncond_label (compress=true)
 .output call_instr (compress=true)
 .output call_instr_arg (compress=true)
 .output call_instr_fn_operand (compress=true)
@@ -575,8 +575,8 @@
 .output mul_instr_first_operand (compress=true)
 .output mul_instr_second_operand (compress=true)
 .output nallocs_by_pt_size (compress=true)
-.output next_instr (compress=true)
-.output next_instr_index (compress=true)
+.output instr_successor (compress=true)
+.output instr_successor_index (compress=true)
 .output non_allocation (compress=true)
 .output nonempty_ptr (compress=true)
 .output nonempty_ptrs (compress=true)
@@ -673,7 +673,7 @@
 .output resume_instr (compress=true)
 .output resume_instr_operand (compress=true)
 .output ret_instr (compress=true)
-.output ret_instr_value (compress=true)
+.output ret_instr_operand (compress=true)
 .output schema_invalid_alias (compress=true)
 .output schema_invalid_constant (compress=true)
 .output schema_invalid_func (compress=true)
@@ -826,7 +826,7 @@
 .output vector_type_has_component (compress=true)
 .output vector_type_has_size (compress=true)
 .output visibility (compress=true)
-.output void_ret_instr (compress=true)
+.output ret_instr_void_ (compress=true)
 .output void_type (compress=true)
 .output vtable (compress=true)
 .output vtable_func (compress=true)
diff --git a/datalog/export/debug-output.dl b/datalog/export/debug-output.dl
index e11e6fd..e945d9a 100644
--- a/datalog/export/debug-output.dl
+++ b/datalog/export/debug-output.dl
@@ -143,13 +143,13 @@
 .output block_predecessors (compress=true)
 .output boolean_type (compress=true)
 .output boolean_vector_type (compress=true)
-.output br_cond_instr (compress=true)
-.output br_cond_instr_condition (compress=true)
-.output br_cond_instr_iffalse_label (compress=true)
-.output br_cond_instr_iftrue_label (compress=true)
+.output br_instr_cond (compress=true)
+.output br_instr_condition (compress=true)
+.output br_instr_false_label (compress=true)
+.output br_instr_true_label (compress=true)
 .output br_instr (compress=true)
-.output br_uncond_instr (compress=true)
-.output br_uncond_instr_dest_label (compress=true)
+.output br_instr_uncond (compress=true)
+.output br_instr_uncond_label (compress=true)
 .output call_instr (compress=true)
 .output call_instr_arg (compress=true)
 .output call_instr_fn_operand (compress=true)
@@ -575,8 +575,8 @@
 .output mul_instr_first_operand (compress=true)
 .output mul_instr_second_operand (compress=true)
 .output nallocs_by_pt_size (compress=true)
-.output next_instr (compress=true)
-.output next_instr_index (compress=true)
+.output instr_successor (compress=true)
+.output instr_successor_index (compress=true)
 .output non_allocation (compress=true)
 .output nonempty_ptr (compress=true)
 .output nonempty_ptrs (compress=true)
@@ -673,7 +673,7 @@
 .output resume_instr (compress=true)
 .output resume_instr_operand (compress=true)
 .output ret_instr (compress=true)
-.output ret_instr_value (compress=true)
+.output ret_instr_operand (compress=true)
 .output schema_invalid_alias (compress=true)
 .output schema_invalid_constant (compress=true)
 .output schema_invalid_func (compress=true)
@@ -826,7 +826,7 @@
 .output vector_type_has_component (compress=true)
 .output vector_type_has_size (compress=true)
 .output visibility (compress=true)
-.output void_ret_instr (compress=true)
+.output ret_instr_void_ (compress=true)
 .output void_type (compress=true)
 .output vtable (compress=true)
 .output vtable_func (compress=true)
diff --git a/datalog/points-to/interprocedural.dl b/datalog/points-to/interprocedural.dl
index 93b8105..759a404 100644
--- a/datalog/points-to/interprocedural.dl
+++ b/datalog/points-to/interprocedural.dl
@@ -179,7 +179,7 @@ func_param_not_by_value(?callee, ?index, ?param) :-
 .decl func_returns_value(?retValue: Operand, ?inFunction: Function)
 
 func_returns_value(?retValue, ?inFunction) :-
-  ret_instr_value(?retInsn, ?retValue),
+  ret_instr_operand(?retInsn, ?retValue),
   instr_func(?retInsn, ?inFunction).
 
 .comp InterpAssignment {
diff --git a/datalog/schema/basic-block.dl b/datalog/schema/basic-block.dl
index c0f4692..1b58f5c 100644
--- a/datalog/schema/basic-block.dl
+++ b/datalog/schema/basic-block.dl
@@ -40,23 +40,23 @@ block_of_label(cat("block:", Label), Label) :-
 
 block_first_instr(BB, First) :-
    instr_block(First, BB),
-   !next_instr(_, First).
+   !instr_successor(_, First).
 
 block_first_instr(BB2, First) :-
-   next_instr(Last, First),
+   instr_successor(Last, First),
    instr_block(Last, BB1),
    instr_block(First, BB2),
    BB1 != BB2.
 
 block_last_instr(BB1, Last) :-
-   next_instr(Last, First),
+   instr_successor(Last, First),
    instr_block(Last, BB1),
    instr_block(First, BB2),
    BB1 != BB2.
 
 block_last_instr(BB, Last) :-
    instr_block(Last, BB),
-   !next_instr(Last, _).
+   !instr_successor(Last, _).
 
 
 //------------------------------------------------------------------------------
@@ -69,7 +69,7 @@ block_last_instr(BB, Last) :-
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   next_instr(Instr, NextInstr),
+   instr_successor(Instr, NextInstr),
    instr_block(Instr, BB1),
    instr_block(NextInstr, BB2),
    !terminator_instr(Instr),
diff --git a/datalog/schema/br-instr.dl b/datalog/schema/br-instr.dl
index af5cfc3..3d9b973 100644
--- a/datalog/schema/br-instr.dl
+++ b/datalog/schema/br-instr.dl
@@ -6,30 +6,30 @@
 .type BrUncondInstruction = BrInstruction
 
 .decl br_instr(instr:BrInstruction)
-.decl br_cond_instr(instr:BrCondInstruction)
-.decl br_uncond_instr(instr:BrUncondInstruction)
+.decl br_instr_cond(instr:BrCondInstruction)
+.decl br_instr_uncond(instr:BrUncondInstruction)
 
 
 instr(v) :- br_instr(v).
 terminator_instr(v) :- br_instr(v).
-br_instr(v) :- br_cond_instr(v).
-br_instr(v) :- br_uncond_instr(v).
+br_instr(v) :- br_instr_cond(v).
+br_instr(v) :- br_instr_uncond(v).
 
 
 //-----------------------------
 // Conditional branch
 //-----------------------------
 
-.decl br_cond_instr_condition(instr:Instruction, cond:Operand)
-.decl br_cond_instr_iftrue_label(instr:Instruction, label:Variable)
-.decl br_cond_instr_iffalse_label(instr:Instruction, label:Variable)
+.decl br_instr_condition(instr:Instruction, cond:Operand)
+.decl br_instr_true_label(instr:Instruction, label:Variable)
+.decl br_instr_false_label(instr:Instruction, label:Variable)
 
 
 //-----------------------------
 // Unconditional branch
 //-----------------------------
 
-.decl br_uncond_instr_dest_label(instr:Instruction, label:Variable)
+.decl br_instr_uncond_label(instr:Instruction, label:Variable)
 
 
 //------------------------------------------------------------------------------
@@ -45,45 +45,45 @@ br_instr(v) :- br_uncond_instr(v).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   !br_cond_instr_condition(Instr, _).
+   br_instr_cond(Instr),
+   !br_instr_condition(Instr, _).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   br_cond_instr_condition(Instr, Cond),
+   br_instr_cond(Instr),
+   br_instr_condition(Instr, Cond),
    operand_has_type(Cond, CondType),
    !int1_type(CondType).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   !br_cond_instr_iftrue_label(Instr, _).
+   br_instr_cond(Instr),
+   !br_instr_true_label(Instr, _).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   !br_cond_instr_iffalse_label(Instr, _).
+   br_instr_cond(Instr),
+   !br_instr_false_label(Instr, _).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   br_cond_instr_iftrue_label(Instr, Label),
+   br_instr_cond(Instr),
+   br_instr_true_label(Instr, Label),
    !variable_is_label(Label).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_cond_instr(Instr),
-   br_cond_instr_iffalse_label(Instr, Label),
+   br_instr_cond(Instr),
+   br_instr_false_label(Instr, Label),
    !variable_is_label(Label).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_uncond_instr(Instr),
-   !br_uncond_instr_dest_label(Instr, _).
+   br_instr_uncond(Instr),
+   !br_instr_uncond_label(Instr, _).
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   br_uncond_instr(Instr),
-   br_uncond_instr_dest_label(Instr, Label),
+   br_instr_uncond(Instr),
+   br_instr_uncond_label(Instr, Label),
    !variable_is_label(Label).
diff --git a/datalog/schema/extractvalue-instr.dl b/datalog/schema/extractvalue-instr.dl
index d36a7db..579d14d 100644
--- a/datalog/schema/extractvalue-instr.dl
+++ b/datalog/schema/extractvalue-instr.dl
@@ -15,7 +15,7 @@ instr(v) :- extractvalue_instr(v).
 .decl extractvalue_instr_nindices(instr:ExtractValueInstruction, total:number)
 .decl extractvalue_instr_index(instr:ExtractValueInstruction, i:number, idx:number)
 
-next_instr_index(Instr, Index, Index + 1) :-
+instr_successor_index(Instr, Index, Index + 1) :-
    extractvalue_instr_index(Instr, Index, _).
 
 
@@ -35,12 +35,12 @@ extractvalue_instrterm_type(Instr, NextIndex, Type) :-
    extractvalue_instrterm_type(Instr, Index, StructType),
    extractvalue_instr_index(Instr, Index, IdxValue),
    struct_type_field(StructType, IdxValue, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 extractvalue_instrterm_type(Instr, NextIndex, Type) :-
    extractvalue_instrterm_type(Instr, Index, ArrayType),
    array_type_has_component(ArrayType, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 extractvalue_instr_value_type(Instr, Type) :-
    extractvalue_instr_nindices(Instr, Total),
diff --git a/datalog/schema/getelementptr-instr.dl b/datalog/schema/getelementptr-instr.dl
index fef6c19..844710b 100644
--- a/datalog/schema/getelementptr-instr.dl
+++ b/datalog/schema/getelementptr-instr.dl
@@ -72,7 +72,7 @@ gep_is_vector_based(Instr) :-
 .decl getelementptr_instr_value_type(instr:GetElementPtrInstruction, type:Type)
 
 
-next_instr_index(Instr, Index, Index + 1) :-
+instr_successor_index(Instr, Index, Index + 1) :-
    getelementptr_instr_index(Instr, Index, _).
 
 getelementptr_instrterm_type(Instr, 1, Type) :-
@@ -87,12 +87,12 @@ getelementptr_instrterm_type(Instr, 1, Type) :-
 getelementptr_instrterm_type(Instr, NextIndex, Type) :-
    getelementptr_instrterm_type(Instr, Index, ArrayType),
    array_type_has_component(ArrayType, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 getelementptr_instrterm_type(Instr, NextIndex, Type) :-
    getelementptr_instrterm_type(Instr, Index, VectorType),
    vector_type_has_component(VectorType, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 getelementptr_instrterm_type(Instr, NextIndex, Type) :-
    getelementptr_instrterm_type(Instr, Index, StructType),
@@ -101,7 +101,7 @@ getelementptr_instrterm_type(Instr, NextIndex, Type) :-
    constant_to_int(FieldIdx, FieldIdxValue),
    int32_type(FieldIdxType),   // c3
    struct_type_field(StructType, FieldIdxValue, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 getelementptr_instr_value_type(Instr, Type) :-
    getelementptr_instr_nindices(Instr, Total),
diff --git a/datalog/schema/insertvalue-instr.dl b/datalog/schema/insertvalue-instr.dl
index b9ce2be..cbb48b4 100644
--- a/datalog/schema/insertvalue-instr.dl
+++ b/datalog/schema/insertvalue-instr.dl
@@ -16,7 +16,7 @@ instr(v) :- insertvalue_instr(v).
 .decl insertvalue_instr_nindices(instr:InsertValueInstruction, total:number)
 .decl insertvalue_instr_index(instr:InsertValueInstruction, i:number, idx:number)
 
-next_instr_index(Instr, Index, Index + 1) :-
+instr_successor_index(Instr, Index, Index + 1) :-
    insertvalue_instr_index(Instr, Index, _).
 
 
@@ -36,12 +36,12 @@ insertvalue_instrterm_type(Instr, NextIndex, Type) :-
    insertvalue_instrterm_type(Instr, Index, StructType),
    insertvalue_instr_index(Instr, Index, IdxValue),
    struct_type_field(StructType, IdxValue, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 insertvalue_instrterm_type(Instr, NextIndex, Type) :-
    insertvalue_instrterm_type(Instr, Index, ArrayType),
    array_type_has_component(ArrayType, Type),
-   next_instr_index(Instr, Index, NextIndex).
+   instr_successor_index(Instr, Index, NextIndex).
 
 insertvalue_instr_value_type(Instr, Type) :-
    insertvalue_instr_nindices(Instr, Total),
diff --git a/datalog/schema/instr.dl b/datalog/schema/instr.dl
index 2470c06..6bd5511 100644
--- a/datalog/schema/instr.dl
+++ b/datalog/schema/instr.dl
@@ -33,7 +33,7 @@ flag(Flag) :- instr_flag(_, Flag).
 
 
 // helpful in avoiding non-termination warnings
-.decl next_instr_index(instr:Instruction, index:number, next_index:number)
+.decl instr_successor_index(instr:Instruction, index:number, next_index:number)
 
 // Position of instr on source code (if debug info is available)
 .decl instr_pos(instr:Instruction, line:LineNumber, column:ColumnNumber)
@@ -44,7 +44,7 @@ flag(Flag) :- instr_flag(_, Flag).
 //------------------------------------
 
 // The next instr in the source file.
-.decl next_instr(instr:Instruction, next:Instruction)
+.decl instr_successor(instr:Instruction, next:Instruction)
 
 // The func that contains the instr
 .decl instr_func(instr:Instruction, func:Function)
diff --git a/datalog/schema/landingpad-instr.dl b/datalog/schema/landingpad-instr.dl
index 23cde7e..a7d6b77 100644
--- a/datalog/schema/landingpad-instr.dl
+++ b/datalog/schema/landingpad-instr.dl
@@ -73,7 +73,7 @@ _landingpad_starting_phi(BB, Instr) :-
 
 _landingpad_starting_phi(BB, NextInstr) :-
    _landingpad_starting_phi(BB, Instr),
-   next_instr(Instr, NextInstr),
+   instr_successor(Instr, NextInstr),
    phi_instr(NextInstr),
    instr_block(NextInstr, BB).
 
@@ -89,7 +89,7 @@ _landingpad_first_nonphi(BB, Instr) :-
 
 _landingpad_first_nonphi(BB, NextInstr) :-
    _landingpad_starting_phi(BB, Instr),
-   next_instr(Instr, NextInstr),
+   instr_successor(Instr, NextInstr),
    !phi_instr(NextInstr),
    instr_block(NextInstr, BB).
 
diff --git a/datalog/schema/ret-instr.dl b/datalog/schema/ret-instr.dl
index f722044..2e95b93 100644
--- a/datalog/schema/ret-instr.dl
+++ b/datalog/schema/ret-instr.dl
@@ -10,13 +10,13 @@ terminator_instr(v) :- ret_instr(v).
 // The ‘ret‘ instr optionally accepts a single
 // argument, the return value.
 
-.decl ret_instr_value(instr:RetInstruction, val:Operand)
-.decl void_ret_instr(instr:RetInstruction)
+.decl ret_instr_operand(instr:RetInstruction, val:Operand)
+.decl ret_instr_void_(instr:RetInstruction)
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   void_ret_instr(Instr),
-   ret_instr_value(Instr, _).
+   ret_instr_void_(Instr),
+   ret_instr_operand(Instr, _).
 
 
 //------------------------------------------------------------------------------
@@ -40,14 +40,14 @@ func_is_wellformed(Func):-
    !func_is_illformed(Func).
 
 func_is_illformed(Func) :-
-   void_ret_instr(Instr),
+   ret_instr_void_(Instr),
    instr_func(Instr, Func),
    func_ty(Func, FuncType),
    func_type_return(FuncType, RetType),
    !void_type(RetType).
 
 func_is_illformed(Func) :-
-   ret_instr_value(Instr, Value),
+   ret_instr_operand(Instr, Value),
    instr_func(Instr, Func),
    func_ty(Func, FuncType),
    func_type_return(FuncType, RetType),
@@ -56,7 +56,7 @@ func_is_illformed(Func) :-
 
 func_is_illformed(Func) :-
    ret_instr(Instr),
-   !void_ret_instr(Instr),
+   !ret_instr_void_(Instr),
    instr_func(Instr, Func),
    func_ty(Func, FuncType),
    func_type_return(FuncType, RetType),
@@ -71,5 +71,5 @@ func_is_illformed(Func) :-
 
 schema_invalid_instr(Instr, __FILE__, __LINE__) :-
    schema_sanity(),
-   ret_instr_value(Instr, Value),
+   ret_instr_operand(Instr, Value),
    !operand_is_firstclass(Value).