add the ability to hash Nats

crates/compiler/builtins/roc/Hash.roc

@@ -14,14 +14,16 @@ interface Hash
         hashI32,
         hashI64,
         hashI128,
+        hashNat,
         complete,
         hashStrBytes,
         hashList,
         hashUnordered,
     ] imports [
+        Bool.{ isEq },
         List,
         Str,
-        Num.{ U8, U16, U32, U64, U128, I8, I16, I32, I64, I128 },
+        Num.{ U8, U16, U32, U64, U128, I8, I16, I32, I64, I128, Nat },
     ]
 
 ## A value that can hashed.
@@ -88,6 +90,21 @@ hashI64 = \hasher, n -> addU64 hasher (Num.toU64 n)
 hashI128 : a, I128 -> a | a has Hasher
 hashI128 = \hasher, n -> addU128 hasher (Num.toU128 n)
 
+## Adds a single Nat to a hasher.
+hashNat : a, Nat -> a | a has Hasher
+hashNat = \hasher, n ->
+    isPlatform32bit =
+        x : Nat
+        x = 0xffff_ffff
+        y = Num.addWrap x 1
+
+        y == 0
+
+    if isPlatform32bit then
+        addU32 hasher (Num.toU32 n)
+    else
+        addU64 hasher (Num.toU64 n)
+
 ## Adds a container of [Hash]able elements to a [Hasher] by hashing each element.
 ## The container is iterated using the walk method passed in.
 ## The order of the elements does not affect the final hash.

crates/compiler/derive_key/src/hash.rs

@@ -174,6 +174,9 @@ const fn num_symbol_to_hash_lambda(symbol: Symbol) -> Option<FlatHash> {
         Symbol::NUM_I128 | Symbol::NUM_SIGNED128 => {
             Some(SingleLambdaSetImmediate(Symbol::HASH_HASH_I128))
         }
+        Symbol::NUM_NAT | Symbol::NUM_NATURAL => {
+            Some(SingleLambdaSetImmediate(Symbol::HASH_HASH_NAT))
+        }
         _ => None,
     }
 }

crates/compiler/module/src/symbol.rs

@@ -1522,10 +1522,11 @@ define_builtins! {
         11 HASH_HASH_I32: "hashI32"
         12 HASH_HASH_I64: "hashI64"
         13 HASH_HASH_I128: "hashI128"
-        14 HASH_COMPLETE: "complete"
-        15 HASH_HASH_STR_BYTES: "hashStrBytes"
-        16 HASH_HASH_LIST: "hashList"
-        17 HASH_HASH_UNORDERED: "hashUnordered"
+        14 HASH_HASH_NAT: "hashNat"
+        15 HASH_COMPLETE: "complete"
+        16 HASH_HASH_STR_BYTES: "hashStrBytes"
+        17 HASH_HASH_LIST: "hashList"
+        18 HASH_HASH_UNORDERED: "hashUnordered"
     }
     14 JSON: "Json" => {
         0 JSON_JSON: "Json"