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-module(list).
-include_lib("eunit/include/eunit.hrl").
-export([length/1, reverse/1, is_empty/1, has_member/2, head/1, tail/1, map/2, new/0, foldl/3, foldr/3]).
length(A) ->
erlang:length(A).
-ifdef(TEST).
length_test() ->
_ = fun(Capture1) -> expect:equal(Capture1, 0) end(length([])),
_ = fun(Capture1) -> expect:equal(Capture1, 1) end(length([1])),
_ = fun(Capture1) -> expect:equal(Capture1, 2) end(length([1, 1])),
fun(Capture1) -> expect:equal(Capture1, 3) end(length([1, 1, 1])).
-endif.
reverse(A) ->
erlang:reverse(A).
-ifdef(TEST).
reverse_test() ->
_ = fun(Capture1) -> expect:equal(Capture1, 0) end(length([])),
fun(Capture1) -> expect:equal(Capture1, 5) end(length([1, 2, 3, 4, 5])).
-endif.
is_empty(List) ->
List =:= [].
-ifdef(TEST).
is_empty_test() ->
_ = expect:true(is_empty([])),
expect:false(is_empty([1])).
-endif.
has_member(List, Elem) ->
case List of
[] ->
false;
[Head | Rest] ->
Head =:= Elem orelse has_member(Rest, Elem)
end.
-ifdef(TEST).
has_member_test() ->
_ = expect:true(has_member([0, 4, 5, 1], 1)),
_ = expect:false(has_member([0, 4, 5, 7], 1)),
expect:false(has_member([], 1)).
-endif.
head(List) ->
case List of
[] ->
{error, empty};
[X | Xs] ->
{ok, X}
end.
-ifdef(TEST).
head_test() ->
_ = fun(Capture1) ->
expect:equal(Capture1, {ok, 0})
end(head([0, 4, 5, 7])),
fun(Capture1) -> expect:equal(Capture1, {error, empty}) end(head([])).
-endif.
tail(List) ->
case List of
[] ->
{error, empty};
[X | Xs] ->
{ok, Xs}
end.
-ifdef(TEST).
tail_test() ->
_ = fun(Capture1) ->
expect:equal(Capture1, {ok, [4, 5, 7]})
end(tail([0, 4, 5, 7])),
_ = fun(Capture1) -> expect:equal(Capture1, {ok, []}) end(tail([0])),
fun(Capture1) -> expect:equal(Capture1, {error, empty}) end(tail([])).
-endif.
do_map(List, Fun, Acc) ->
case List of
[] ->
reverse(Acc);
[X | Xs] ->
do_map(Xs, Fun, [Fun(X) | Acc])
end.
map(List, Fun) ->
do_map(List, Fun, []).
-ifdef(TEST).
map_test() ->
_ = fun(Capture1) ->
expect:equal(Capture1, [])
end(fun(Capture1) -> map(Capture1, fun(X) -> X * 2 end) end([])),
fun(Capture1) ->
expect:equal(Capture1, [0, 8, 10, 14, 6])
end(fun(Capture1) ->
map(Capture1, fun(X) -> X * 2 end)
end([0, 4, 5, 7, 3])).
-endif.
new() ->
[].
-ifdef(TEST).
new_test() ->
fun(Capture1) -> expect:equal(Capture1, []) end(new()).
-endif.
foldl(List, Acc, Fun) ->
case List of
[] ->
Acc;
[X | Rest] ->
foldl(Rest, Fun(X, Acc), Fun)
end.
-ifdef(TEST).
foldl_test() ->
fun(Capture1) ->
expect:equal(Capture1, [3, 2, 1])
end(fun(Capture1) ->
foldl(Capture1, [], fun(X, Acc) -> [X | Acc] end)
end([1, 2, 3])).
-endif.
foldr(List, Acc, Fun) ->
case List of
[] ->
Acc;
[X | Rest] ->
Fun(X, foldr(Rest, Acc, Fun))
end.
-ifdef(TEST).
foldr_test() ->
fun(Capture1) ->
expect:equal(Capture1, [1, 2, 3])
end(fun(Capture1) ->
foldr(Capture1, [], fun(X, Acc) -> [X | Acc] end)
end([1, 2, 3])).
-endif.
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