Release 0.6.4

🚀 pyochain 0.6.4 — Release Notes

Date: 2026-01-09 📅

🆕 Highlights

• Methods Reorganization: PyoIterable → Iter
• Deprecated Methods Removal from Dict and Option
• Option.if_true() API Improvement
• Various documentation improvements

🔄 API Changes

Migrated: from PyoIterable to Iter

Several methods have been moved from the PyoIterable base trait to Iter only, as they don't make sense on unordered collections like Dict and Set:

• all_equal()
• all_unique()
• argmax()
• argmin()
• is_sorted()

Why? Dict, Set, and SetMut are unordered/non-comparable collections. Having sorting/uniqueness checks on them is semantically incorrect.

Migration:

# Before (on Seq, Vec)
seq.is_sorted()
seq.all_unique()
seq.argmax()

# After
seq.iter().is_sorted()
seq.iter().all_unique()
seq.iter().argmax()

Removed: Deprecated Dict Methods

The following deprecated methods have been permanently removed from Dict:

• ❌ map_items()
• ❌ map_keys()
• ❌ map_values()
• ❌ filter_items()
• ❌ filter_keys()
• ❌ filter_values().

Migration: Use .iter().map_star(...).collect(pc.Dict) or .iter().filter_star(...).collect(pc.Dict) instead:

# Before
d.map_keys(str.lower)
d.filter_values(lambda v: v > 0)

# After
d.iter().map_star(lambda k, v: (str.lower(k), v)).collect(pc.Dict)
d.iter().filter_star(lambda k, v: v > 0).collect(pc.Dict)

Note:
You can still chain dictionary transformations with .into() calls wrapping cytoolz functions, e.g.:

import cytoolz as cz

import pyochain as pc

res = pc.Dict.from_kwargs(a=1, b=2).into(
    lambda d: pc.Dict(cz.dicttoolz.keyfilter(lambda k: k == "a", d))
)
# Dict('a': 1)

Why?

• Encourages explicit chaining via Iter.
• Discourage long chain of transformation on dictionaries, which is inefficient since each step create a new intermediate dict -> hashing, no-lazy evaluation, no unpacking for *_item() methods, etc...
• When the new frozendict type from PEP 814 is introduced, it will might make sense to bring those methods back, since they internally always returned new dict instances under the hood.

Removed: Option.from_() Deprecated Method

The deprecated Option.from_() method has been removed. Use Option() constructor instead:

# Before
pc.Option.from_(value)

# After
pc.Option(value)  # Same behavior

Enhanced: Option.if_true() Now Applies Predicate to Value

The Option.if_true() method has been improved to apply the predicate directly to the provided value, making it more ergonomic:

Before:

# Predicate received NO arguments - had to capture external state
pc.Option.if_true(42, predicate=lambda: external_check)

After:

# Predicate now receives the value itself
pc.Option.if_true(42, predicate=lambda x: x == 42)
pc.Option.if_true(42, predicate=lambda x: x > 0)

# Can call methods directly on the value
from pathlib import Path
pc.Option.if_true(Path("file.txt"), predicate=Path.exists)
pc.Option.if_true(Path("file.txt"), predicate=lambda p: p.exists())

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