[issue20481] Clarify type coercion rules in statistics module

[Nick Coghlan]

New submission from Nick Coghlan:

I haven't completely following the type coercion discussion on python-ideas. but the statistics module at least needs a docs clarification (to explain that the current behaviour when mixing input types is not fully defined, especially when Decimal is involved), and potentially a behavioural change to disallow certain type combinations where the behaviour may change in the future (see
https://mail.python.org/pipermail/python-ideas/2014-February/025214.html for example)

Either option seems reasonable to me (with a slight preference for the latter), but it's at least clear that we need to avoid locking ourselves into the exact coercion behaviour of the current implementation indefinitely.

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components: Library (Lib)
messages: 209934
nosy: gregory.p.smith, larry, ncoghlan, oscarbenjamin, stevenjd, wolma
priority: release blocker
severity: normal
stage: needs patch
status: open
title: Clarify type coercion rules in statistics module
type: behavior
versions: Python 3.4

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<http://bugs.python.org/issue20481>
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