spell backward curriculum (#327)

Co-authored-by: Andreas Köpf <andreas.koepf@xamla.com>

reasoning_gym/algorithmic/spell_backward.py

@@ -5,6 +5,7 @@ from dataclasses import dataclass
 from random import Random
 from typing import Any, Optional
 
+from ..coaching import AttributeType, BaseCurriculum, RangeAttributeDefinition
 from ..data import read_data_file
 from ..factory import ProceduralDataset, register_dataset
 
@@ -14,12 +15,14 @@ class SpellBackwardConfig:
     """Configuration for spelling words backward task generation"""
 
     min_word_len: int = 3  # Minimum word length
+    max_word_len: int = 20  # Maximum word length
     seed: Optional[int] = None
     size: int = 500  # Virtual dataset size
 
     def validate(self) -> None:
         """Validate configuration parameters"""
         assert self.min_word_len > 0, "min_word_len must be positive"
+        assert self.max_word_len >= self.min_word_len, "max_word_len must be >= min_word_len"
 
 
 class SpellBackwardDataset(ProceduralDataset):
@@ -32,7 +35,9 @@ class SpellBackwardDataset(ProceduralDataset):
         text = read_data_file("in_the_year_2889.txt")
         # Extract words and clean them to contain only alphanumeric characters
         self.words = [
-            word for word in re.findall(r"\b\w+\b", text) if word.isalnum() and len(word) >= config.min_word_len
+            word
+            for word in re.findall(r"\b\w+\b", text)
+            if word.isalnum() and config.min_word_len <= len(word) <= config.max_word_len
         ]
 
     def __getitem__(self, idx: int) -> dict:
@@ -46,7 +51,11 @@ class SpellBackwardDataset(ProceduralDataset):
         return {
             "question": f"Spell this word backward (example: sun -> nus): {word}",
             "answer": answer,
-            "metadata": {"word": word, "word_len": len(word)},
+            "metadata": {
+                "word": word,
+                "word_len": len(word),
+                "difficulty": {"word_len": (self.config.min_word_len, self.config.max_word_len)},
+            },
         }
 
     def score_answer(self, answer: Optional[str], entry: dict[str, Any]) -> float:
@@ -63,4 +72,23 @@ class SpellBackwardDataset(ProceduralDataset):
         return reward
 
 
-register_dataset("spell_backward", SpellBackwardDataset, SpellBackwardConfig)
+class SpellBackwardCurriculum(BaseCurriculum):
+    def __init__(self):
+        super().__init__(SpellBackwardCurriculum.__name__, SpellBackwardConfig)
+
+        # Define attributes
+        self._define_attributes(
+            RangeAttributeDefinition(
+                name="word_len",
+                levels=[5, 10, 20, 30],
+                default_level=1,
+                description="Word length",
+                attr_type=AttributeType.APPEND,
+                min_value=3,
+                lower_field_name="min_word_len",
+                upper_field_name="max_word_len",
+            ),
+        )
+
+
+register_dataset("spell_backward", SpellBackwardDataset, SpellBackwardConfig, SpellBackwardCurriculum)