[MLX LM] Sampler refactor + a few improvements (#1094)

* starting

* refactor sampler/processor and a few improvements

* fix stream

* fix stream generate

* fix eos handling in stream generate

llms/mlx_lm/generate.py

@@ -13,6 +13,8 @@ DEFAULT_PROMPT = "hello"
 DEFAULT_MAX_TOKENS = 100
 DEFAULT_TEMP = 0.0
 DEFAULT_TOP_P = 1.0
+DEFAULT_MIN_P = 0.0
+DEFAULT_MIN_TOKENS_TO_KEEP = 1
 DEFAULT_SEED = 0
 DEFAULT_MODEL = "mlx-community/Llama-3.2-3B-Instruct-4bit"
 DEFAULT_QUANTIZED_KV_START = 5000
@@ -52,6 +54,7 @@ def setup_arg_parser():
     )
     parser.add_argument(
         "--prompt",
+        "-p",
         default=DEFAULT_PROMPT,
         help="Message to be processed by the model ('-' reads from stdin)",
     )
@@ -68,6 +71,15 @@ def setup_arg_parser():
     parser.add_argument(
         "--top-p", type=float, default=DEFAULT_TOP_P, help="Sampling top-p"
     )
+    parser.add_argument(
+        "--min-p", type=float, default=DEFAULT_MIN_P, help="Sampling min-p"
+    )
+    parser.add_argument(
+        "--min-tokens-to-keep",
+        type=float,
+        default=DEFAULT_MIN_TOKENS_TO_KEEP,
+        help="Minimum tokens to keep for min-p sampling.",
+    )
     parser.add_argument("--seed", type=int, default=DEFAULT_SEED, help="PRNG seed")
     parser.add_argument(
         "--ignore-chat-template",
@@ -247,6 +259,8 @@ def main():
         formatter=formatter,
         temp=args.temp,
         top_p=args.top_p,
+        min_p=args.min_p,
+        min_tokens_to_keep=args.min_tokens_to_keep,
         max_kv_size=args.max_kv_size,
         prompt_cache=prompt_cache if using_cache else None,
         kv_bits=args.kv_bits,