Raisin-4B is a lightweight (~3.8B parameter), long-context language model fine-tuned and merged by Rapple ML. Built specifically for multi-step reasoning, logical planning, and long-doc processing, Raisin-4B generates explicit <think> ... </think> Chain-of-Thought (CoT) traces before delivering final outputs.

By leveraging YaRN (Yet another RoPE eXtension) scaling alongside DARE-TIES parameter merging, Raisin-4B provides a massive 131,072-token context window while retaining tight instruction adherence and a low memory footprint.

📊 Model Architecture & Metadata

Attribute	Specification
Organization	Rapple ML
Architecture	Dense Decoder-Only Transformer (`Phi3ForCausalLM`)
Base Model	`microsoft/Phi-3.5-mini-instruct`
Active Parameters	~3.8 Billion
Context Length	131,072 Tokens (128k)
Position Embedding	Su-RoPE / YaRN (Factor 4.0)
Precision	`bfloat16` / `float16`
Fine-Tuning Stack	Unsloth + TRL (`SFTTrainer`)
Merge Method	DARE-TIES (`mergekit`)

💻 Quickstart Guide

python

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "RappleML/Raisin-4B"

tokenizer = AutoTokenizer.from_pretrained(model_id, trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained(
    model_id,
    torch_dtype=torch.bfloat16,
    device_map="auto",
    trust_remote_code=True
)

prompt = "<|user|>\nAnalyze this problem and outline a plan before answering: How many r's are in strawberry?<|end|>\n<|assistant|>\n"
inputs = tokenizer(prompt, return_tensors="pt").to("cuda")

outputs = model.generate(
    **inputs,
    max_new_tokens=1024,
    temperature=0.6,
    top_p=0.95,
    do_sample=True
)

print(tokenizer.decode(outputs[0], skip_special_tokens=True))

⚙️ Prompt Template

Raisin-4B uses the standard Phi-3 Chat Template. To activate reasoning mode, prompt the assistant to output a <think> block:

text

<|user|>
[YOUR PROMPT / INSTRUCTION HERE]<|end|>
<|assistant|>
<think>
[RAISIN WILL GENERATE STEP-BY-STEP REASONING HERE]
</think>
[FINAL ANSWER]

🛠️ Training & Merge Details

Supervised Fine-Tuning (SFT): Trained with unsloth and unsloth_zoo on a curated reasoning slice from open-r1/OpenR1-Math-220k.
Merging Strategy: Merged via mergekit using DARE-TIES ($0.6$ density, $0.5$ weight) with microsoft/Phi-3.5-mini-instruct to eliminate redundant parameter shifts and preserve base capabilities.
Context Extension: Configured with a 4.0x YaRN RoPE scaling setup to extend positional context to 131,072 tokens.

Developed with ❤️ by Rapple ML