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itertools provides iterator building blocks inspired by constructs from APL, Haskell, and SML. [S1]

Iterator algebra

iterator building blocks inspired by constructs from APL, Haskell, and SML. [S1]

memory efficient tools that are useful by themselves or in combination. [S1]

With functools

higher-order functions: functions that act on or return other functions. [S2]

Claims

• id: C1 claim: itertools builds on classic iterator blocks. source: S1 evidence: "iterator building blocks inspired by constructs from APL, Haskell, and SML."

• id: C2 claim: The tools are memory efficient alone or combined. source: S1 evidence: "memory efficient tools that are useful by themselves or in combination."

• id: C3 claim: functools is for higher-order functions. source: S2 evidence: "higher-order functions: functions that act on or return other functions."

• id: C4 claim: reduce applies a two-arg function cumulatively. source: S2 evidence: "Apply function of two arguments cumulatively to the items of iterable"

Sources

• [S1] itertools — Functions creating iterators for efficient looping. Python Software Foundation. https://docs.python.org/3/library/itertools.html . License: PSF License Version 2. Accessed 2026-11-06.

• [S2] functools — Higher-order functions and operations on callable objects. Python Software Foundation. https://docs.python.org/3/library/functools.html . License: PSF License Version 2. Accessed 2026-11-06.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Source: Python Software Foundation (Python 3 docs). PSF License Version 2 (https://docs.python.org/3/license.html).

@misc{iil_note_936fwscy,
  author = {{iinventedlight}},
  title = {{itertools: memory-efficient iterator tools}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-06},
  url = {https://iinventedlight.com/library/notes/python-itertools/},
  note = {Permanent ID iil:note:936fwscy. License: CC-BY-4.0.},
}

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