diff --git a/compiler/builtins/bitcode/src/dict.zig b/compiler/builtins/bitcode/src/dict.zig
index d68f64e473..9e65870eea 100644
--- a/compiler/builtins/bitcode/src/dict.zig
+++ b/compiler/builtins/bitcode/src/dict.zig
@@ -1,23 +1,111 @@
 const std = @import("std");
 const testing = std.testing;
 const expectEqual = testing.expectEqual;
+const mem = std.mem;
+const Allocator = mem.Allocator;
+
+const level_size = 32;
+
+const InPlace = packed enum(u8) {
+    InPlace,
+    Clone,
+};
+
+const Slot = packed enum(u8) {
+    Empty,
+    Filled,
+    PreviouslyFilled,
+};
 
 pub const RocDict = extern struct {
     dict_bytes: ?[*]u8,
-    dict_len: usize,
+    dict_slot_len: usize,
+    dict_entries_len: usize,
 
-    pub fn init() RocDict {
-        return RocDict{ .dict_len = 0, .dict_bytes = null };
+    pub fn init(allocator: *Allocator, bytes_ptr: [*]const u8, number_of_slots: usize, number_of_entries: usize, key_size: usize, value_size: usize) RocDict {
+        var result = RocDict.allocate(
+            allocator,
+            InPlace.Clone,
+            number_of_slots,
+            number_of_entries,
+            key_size,
+            value_size,
+        );
+
+        @memcpy(result.asU8ptr(), bytes_ptr, number_of_slots);
+
+        return result;
+    }
+
+    pub fn deinit(self: RocDict, allocator: *Allocator) void {
+        const dict_bytes_ptr: [*]u8 = self.dict_bytes orelse unreachable;
+        const dict_bytes: []u8 = dict_bytes_ptr[0..self.dict_slot_len];
+        allocator.free(dict_bytes);
+    }
+
+    pub fn allocate(
+        allocator: *Allocator,
+        result_in_place: InPlace,
+        number_of_slots: usize,
+        number_of_entries: usize,
+        key_size: usize,
+        value_size: usize,
+    ) RocDict {
+        const slot_size = @sizeOf(Slot) + key_size + value_size;
+
+        const length = @sizeOf(usize) + (number_of_slots * slot_size);
+
+        var new_bytes: []usize = allocator.alloc(usize, length) catch unreachable;
+
+        if (result_in_place == InPlace.InPlace) {
+            new_bytes[0] = @intCast(usize, number_of_slots);
+        } else {
+            const v: isize = std.math.minInt(isize);
+            new_bytes[0] = @bitCast(usize, v);
+        }
+
+        var first_slot = @ptrCast([*]align(@alignOf(usize)) u8, new_bytes);
+        first_slot += @sizeOf(usize);
+
+        return RocDict{
+            .dict_bytes = first_slot,
+            .dict_slot_len = number_of_slots,
+            .dict_entries_len = number_of_entries,
+        };
+    }
+
+    pub fn asU8ptr(self: RocDict) [*]u8 {
+        return @ptrCast([*]u8, self.dict_bytes);
     }
 
     pub fn contains(self: RocDict, key_size: usize, key_ptr: *const c_void, hash_code: u64) bool {
         return false;
     }
+
+    pub fn len(self: RocDict) usize {
+        return self.dict_entries_len;
+    }
+
+    pub fn isEmpty(self: RocDict) bool {
+        return self.len() == 0;
+    }
+
+    pub fn clone(self: RocDict, allocator: *Allocator, in_place: InPlace, key_size: usize, value_size: usize) RocDict {
+        var new_dict = RocDict.init(allocator, self.dict_slot_len, self.dict_entries_len, key_size, value_size);
+
+        var old_bytes: [*]u8 = @ptrCast([*]u8, self.dict_bytes);
+        var new_bytes: [*]u8 = @ptrCast([*]u8, new_dict.dict_bytes);
+
+        @memcpy(new_bytes, old_bytes, self.dict_slot_len);
+
+        return new_dict;
+    }
+    // pub fn insert(self: RocDict, key_size: usize, key_ptr: *const c_void, value_ptr: *const c_void)
 };
 
 // Dict.empty
-pub fn dictEmpty() callconv(.C) RocDict {
-    return RocDict.init();
+pub fn dictEmpty(allocator: *Allocator, key_size: usize, value_size: usize) callconv(.C) RocDict {
+    return RocDict.init(allocator, "", 0, 0, key_size, value_size);
 }
 
 // Dict.len
@@ -26,7 +114,12 @@ pub fn dictLen(dict: RocDict) callconv(.C) usize {
 }
 
 test "RocDict.init() contains nothing" {
-    const dict = RocDict.init();
+    const key_size = @sizeOf(usize);
+    const value_size = @sizeOf(usize);
+
+    const dict = dictEmpty(testing.allocator, key_size, value_size);
 
     expectEqual(false, dict.contains(4, @ptrCast(*const c_void, &""), 9));
+
+    dict.deinit(testing.allocator);
 }
diff --git a/compiler/builtins/bitcode/src/str.zig b/compiler/builtins/bitcode/src/str.zig
index 79403bbd22..c16d0acff3 100644
--- a/compiler/builtins/bitcode/src/str.zig
+++ b/compiler/builtins/bitcode/src/str.zig
@@ -40,8 +40,6 @@ pub const RocStr = extern struct {
     // This clones the pointed-to bytes if they won't fit in a
     // small string, and returns a (pointer, len) tuple which points to them.
     pub fn init(allocator: *Allocator, bytes_ptr: [*]const u8, length: usize) RocStr {
-        const roc_str_size = @sizeOf(RocStr);
-
         var result = RocStr.allocate(allocator, InPlace.Clone, length);
         @memcpy(result.asU8ptr(), bytes_ptr, length);