Use 32 bits seed for generating terms

1 files changed, 8 insertions, 6 deletions

diff --git a/rust/src/lambda.rs b/rust/src/lambda.rs
index 3a8372b..8ac3e46 100644
--- a/rust/src/lambda.rs
+++ b/rust/src/lambda.rs
@@ -117,7 +117,7 @@ pub fn generate_expr(size: u32, runner: &mut TestRunner) -> Value {
         6 => simple_lambda().new_tree(runner).unwrap().current(),
         7 => app_to_lambda().new_tree(runner).unwrap().current(),
         8 => multi_app().new_tree(runner).unwrap().current(),
-        9 => any::<u16>()
+        9 => any::<u32>()
             .prop_flat_map(gen_terms)
             .new_tree(runner)
             .unwrap()
@@ -162,14 +162,16 @@ fn app_to_lambda() -> impl Strategy<Value = Value> {
     (lam, arg).prop_map(|(l, a)| Value::App(Box::new(l), Box::new(a)))
 }
 
-fn pairing(k: u16) -> (u16, u16) {
-    let a = ((((8 * (k as u32) + 1) as f32).sqrt() - 1.0) / 2.0).floor();
+/// Cantor pairing function
+/// See https://en.wikipedia.org/wiki/Pairing_function
+fn pairing(k: u32) -> (u32, u32) {
+    let a = ((((8 * (k as u64) + 1) as f64).sqrt() - 1.0) / 2.0).floor();
     let b = (a * (a + 1.0)) / 2.0;
-    let n = (k as f32) - b;
-    (n as u16, (a - n) as u16)
+    let n = (k as f64) - b;
+    (n as u32, (a - n) as u32)
 }
 
-fn gen_terms(u: u16) -> impl Strategy<Value = Value> {
+fn gen_terms(u: u32) -> impl Strategy<Value = Value> {
     if u % 2 != 0 {
         let j = (u - 1) / 2;
         if j % 2 == 0 {