Replace u64 with i64 in client-facing code, force conversions (#6)

src/lib.rs

@@ -36,15 +36,15 @@ unsafe impl ocaml::ToValue for RsddVarLabel {
 unsafe impl ocaml::FromValue for RsddVarLabel {
     fn from_value(v: ocaml::Value) -> Self {
         let i = unsafe { v.int64_val() };
-        RsddVarLabel(VarLabel::new(i as u64))
+        RsddVarLabel(VarLabel::new(i.try_into().unwrap()))
     }
 }
 
 // disc/dice interface
 
 #[ocaml::func]
 #[ocaml::sig("int64 -> rsdd_bdd_builder")]
-pub fn mk_bdd_builder_default_order(num_vars: u64) -> ocaml::Pointer<RsddBddBuilder> {
+pub fn mk_bdd_builder_default_order(num_vars: i64) -> ocaml::Pointer<RsddBddBuilder> {
     RsddBddBuilder(RobddBuilder::<AllIteTable<BddPtr>>::new(
         VarOrder::linear_order(num_vars as usize),
     ))
@@ -56,9 +56,9 @@ pub fn mk_bdd_builder_default_order(num_vars: u64) -> ocaml::Pointer<RsddBddBuil
 pub fn bdd_new_var(
     builder: &'static RsddBddBuilder,
     polarity: bool,
-) -> (u64, ocaml::Pointer<RsddBddPtr>) {
+) -> (i64, ocaml::Pointer<RsddBddPtr>) {
     let (lbl, ptr) = builder.0.new_var(polarity);
-    (lbl.value(), RsddBddPtr(ptr).into())
+    (lbl.value().try_into().unwrap(), RsddBddPtr(ptr).into())
 }
 
 #[ocaml::func]
@@ -139,10 +139,10 @@ pub fn bdd_eq(builder: &'static RsddBddBuilder, a: &RsddBddPtr, b: &RsddBddPtr)
 
 #[ocaml::func]
 #[ocaml::sig("rsdd_bdd_ptr -> int64")]
-pub fn bdd_topvar(bdd: &RsddBddPtr) -> u64 {
+pub fn bdd_topvar(bdd: &RsddBddPtr) -> i64 {
     match (bdd.0).var_safe() {
-        Some(x) => x.value(),
-        None => 0, // TODO: provide a better version for this, maybe a Maybe/Option?
+        Some(x) => x.value().try_into().unwrap(),
+        None => -1, // TODO: provide a better version for this, maybe a Maybe/Option?
     }
 }
 
@@ -180,7 +180,7 @@ pub fn new_wmc_params_r(weights: ocaml::List<(f64, f64)>) -> ocaml::Pointer<Rsdd
             .enumerate()
             .map(|(index, (a, b))| {
                 (
-                    VarLabel::new(index as u64),
+                    VarLabel::new(index.try_into().unwrap()),
                     (RealSemiring(*a), RealSemiring(*b)),
                 )
             }),
@@ -202,7 +202,7 @@ ocaml::custom!(RsddWmcParamsEU);
 pub fn bdd_bb(
     bdd: &'static RsddBddPtr,
     join_vars: ocaml::List<RsddVarLabel>,
-    num_vars: u64,
+    num_vars: i64,
     wmc: &RsddWmcParamsEU,
 ) -> (
     ocaml::Pointer<RsddExpectedUtility>,
@@ -225,7 +225,7 @@ pub fn bdd_bb(
 pub fn bdd_meu(
     bdd: &'static RsddBddPtr,
     decision_vars: ocaml::List<RsddVarLabel>,
-    num_vars: u64,
+    num_vars: i64,
     wmc: &RsddWmcParamsEU,
 ) -> (
     ocaml::Pointer<RsddExpectedUtility>,
@@ -255,7 +255,7 @@ pub fn new_wmc_params_eu(
             .enumerate()
             .map(|(index, (a, b))| {
                 (
-                    VarLabel::new(index as u64),
+                    VarLabel::new(index.try_into().unwrap()),
                     (ExpectedUtility(a.0, a.1), ExpectedUtility(b.0, b.1)),
                 )
             }),
@@ -282,15 +282,15 @@ pub fn bdd_builder_compile_cnf(
 
 #[ocaml::func]
 #[ocaml::sig("rsdd_bdd_builder -> rsdd_bdd_ptr -> int64")]
-pub fn bdd_model_count(builder: &'static RsddBddBuilder, bdd: &'static RsddBddPtr) -> u64 {
+pub fn bdd_model_count(builder: &'static RsddBddBuilder, bdd: &'static RsddBddPtr) -> i64 {
     let num_vars = builder.0.num_vars();
     let smoothed = builder.0.smooth(bdd.0, num_vars);
     let unweighted_params: WmcParams<FiniteField<{ primes::U64_LARGEST }>> =
         WmcParams::new(HashMap::from_iter(
-            (0..num_vars as u64)
+            (0..num_vars.try_into().unwrap())
                 .map(|v| (VarLabel::new(v), (FiniteField::one(), FiniteField::one()))),
         ));
 
     let mc = smoothed.unsmoothed_wmc(&unweighted_params).value();
-    mc as u64
+    mc.try_into().unwrap()
 }