Add isSubsequenceOf to Data.List

Niklas Hambüchen suggested that we add the dual of subsequences, isSubsequenceOf (like isPrefixOf to inits & isSuffixOf to tails)[1]. It was a simple and noncontroversial proposal which received unanimous +1s.

[1]

https://www.haskell.org/pipermail/libraries/2014-November/024063.html

Trac metadata

Trac field	Value
Version	7.8.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
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Blocking
CC	ekmett, hvr
Operating system
Architecture

changed milestone to %7.10.1

changed weight to 5

added Tfeature request Trac import core libraries labels

mentioned in commit 40b1ee40

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added report impact label

added Pnormal label