refactor: replace open-write-close patterns with pathlib methods

nanochat/common.py

@@ -85,8 +85,7 @@ def download_file_with_lock(url, filename, postprocess_fn=None):
             content = response.read() # bytes
 
         # Write to local file
-        with file_path.open('wb') as f:
-            f.write(content)
+        file_path.write_bytes(content)
         print(f"Downloaded to {file_path}")
 
         # Run the postprocess function if provided

nanochat/tokenizer.py

@@ -392,6 +392,5 @@ def get_token_bytes(device="cpu"):
     tokenizer_dir = base_dir / "tokenizer"
     token_bytes_path = tokenizer_dir / "token_bytes.pt"
     assert token_bytes_path.exists(), f"Token bytes not found at {token_bytes_path}? It gets written by tok_train.py"
-    with token_bytes_path.open("rb") as f:
-        token_bytes = torch.load(f, map_location=device)
+    token_bytes = torch.load(token_bytes_path, map_location=device)
     return token_bytes

scripts/tok_train.py

@@ -85,8 +85,7 @@ for token_id in range(vocab_size):
         token_bytes.append(id_bytes)
 token_bytes = torch.tensor(token_bytes, dtype=torch.int32, device='cpu')
 token_bytes_path = tokenizer_dir / "token_bytes.pt"
-with token_bytes_path.open("wb") as f:
-    torch.save(token_bytes, f)
+torch.save(token_bytes, token_bytes_path)
 print(f"Saved token_bytes to {token_bytes_path}")
 
 # Log to report