How to terminate early a functional computation

Question

Problem description: Given a list $A=\{1,2,0,7,0,-1,2,6,\ldots\}$ and a list $B=\{0,7,0\}$ write a program that determines whether $B$ appears in $A$ or not. Note: the order of $B$'s items does matter.

Functional way:

MemberQ[Partition[A, 3, 1], B]

The disadvantage of this way is that the whole list $A$ is processed even if $B$ is in the very start of $A$. Compare with the following code which terminates early if $B$ is found in $A$:

Procedural way:

found = False;
L = Length@A;
For[i = 1, i <= (L - 2) && !found, i++,
found = Take[A, {i, i + 2}] == B]

Question: Is there a functional way of solving the problem that does not need to scan/process all of $A$'s elements ?

P.S. Feel free to edit the title.

Answer 1

More recent (10.1+) versions of Mathematica feature the SequencePosition function, which can be told to stop after the first match, like so:

SeedRandom[1337];
a = RandomInteger[{1, 10}, 10000];
b = {1, 7, 1};

SequencePosition[a, b, 1] // AbsoluteTiming
(* {0.000175, {{88, 90}}} *)

This is quite a bit faster than the MemberQ/Partition-based approach:

MemberQ[Partition[a, 3, 1], b, {1}] // AbsoluteTiming
(* {0.00199, True} *)

As a word of warning, you can use more general patterns with SequencePosition and similar functions, but as of version 10.3 the performance is only really good with fixed patterns like {1, 7, 1}.

EDIT to add: It seems to provide a similar speedup over other solutions, like in @belisarius' comment:

MatchQ[a, {___, PatternSequence @@ b, ___}] // AbsoluteTiming
(* {0.019747, True} *)