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forestbelton/zipr.erl

Last active December 25, 2015 13:59
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zipr.erl
-module(zipr).
-export([new/1, cur/1, to_list/1, next/1, prev/1, addl/2, addr/2]).
new(X) -> {[], X, []}.
cur({_L, X, _R}) -> X.
to_list({L, X, R}) -> lists:reverse(L) ++ [X] ++ R.
next({L, X, [H|R]}) -> {[X]++L, H, R}.
prev({[H|L], X, R}) -> {L, X, [H]++R}.
addl({L, X, R}, X1) -> {L, X1, [X]++R}.
addr({L, X, R}, X1) -> {[X]++L, X1, R}.
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