Merge pull request #4696 from roc-lang/hash-nat

add the ability to hash Nats

crates/compiler/builtins/roc/Dict.roc

@@ -821,6 +821,13 @@ expect
     |> len
     |> Bool.isEq 0
 
+# Makes sure a Dict with Nat keys works
+expect
+    empty
+    |> insert 7nat "Testing"
+    |> get 7
+    |> Bool.isEq (Ok "Testing")
+
 # We have decided not to expose the standard roc hashing algorithm.
 # This is to avoid external dependence and the need for versioning.
 # The current implementation is a form of [Wyhash final3](https://github.com/wangyi-fudan/wyhash/blob/a5995b98ebfa7bd38bfadc0919326d2e7aabb805/wyhash.h).

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"
+        14 HASH_HASH_NAT: "hashNat"
-        15 HASH_HASH_STR_BYTES: "hashStrBytes"
+        15 HASH_COMPLETE: "complete"
-        16 HASH_HASH_LIST: "hashList"
+        16 HASH_HASH_STR_BYTES: "hashStrBytes"
-        17 HASH_HASH_UNORDERED: "hashUnordered"
+        17 HASH_HASH_LIST: "hashList"
+        18 HASH_HASH_UNORDERED: "hashUnordered"
     }
     14 JSON: "Json" => {
         0 JSON_JSON: "Json"

crates/compiler/test_mono/generated/dict.txt

@@ -1,22 +1,22 @@
 procedure Dict.1 ():
-    let Dict.518 : List {[], []} = Array [];
+    let Dict.520 : List {[], []} = Array [];
-    let Dict.525 : U64 = 0i64;
+    let Dict.527 : U64 = 0i64;
-    let Dict.526 : U64 = 8i64;
+    let Dict.528 : U64 = 8i64;
-    let Dict.519 : List U64 = CallByName List.11 Dict.525 Dict.526;
+    let Dict.521 : List U64 = CallByName List.11 Dict.527 Dict.528;
-    let Dict.522 : I8 = CallByName Dict.34;
+    let Dict.524 : I8 = CallByName Dict.34;
-    let Dict.523 : U64 = 8i64;
+    let Dict.525 : U64 = 8i64;
-    let Dict.520 : List I8 = CallByName List.11 Dict.522 Dict.523;
+    let Dict.522 : List I8 = CallByName List.11 Dict.524 Dict.525;
-    let Dict.521 : U64 = 0i64;
+    let Dict.523 : U64 = 0i64;
-    let Dict.517 : {List {[], []}, List U64, List I8, U64} = Struct {Dict.518, Dict.519, Dict.520, Dict.521};
+    let Dict.519 : {List {[], []}, List U64, List I8, U64} = Struct {Dict.520, Dict.521, Dict.522, Dict.523};
-    ret Dict.517;
+    ret Dict.519;
 
 procedure Dict.34 ():
-    let Dict.524 : I8 = -128i64;
+    let Dict.526 : I8 = -128i64;
-    ret Dict.524;
+    ret Dict.526;
 
-procedure Dict.4 (Dict.505):
+procedure Dict.4 (Dict.507):
-    let Dict.85 : U64 = StructAtIndex 3 Dict.505;
+    let Dict.85 : U64 = StructAtIndex 3 Dict.507;
-    dec Dict.505;
+    dec Dict.507;
     ret Dict.85;
 
 procedure List.11 (List.113, List.114):