Exercism: Accumulate

erlang/accumulate/.exercism/config.json

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+{
+  "blurb": "Implement the `accumulate` operation, which, given a collection and an operation to perform on each element of the collection, returns a new collection containing the result of applying that operation to each element of the input collection.",
+  "authors": [],
+  "contributors": [
+    "adolfopa",
+    "ErikSchierboom",
+    "etrepum",
+    "iHiD",
+    "JordanAdams",
+    "juhlig",
+    "kytrinyx",
+    "magthe",
+    "NobbZ",
+    "tmcgilchrist",
+    "xymbol"
+  ],
+  "files": {
+    "solution": [
+      "src/accumulate.erl"
+    ],
+    "test": [
+      "test/accumulate_tests.erl"
+    ],
+    "example": [
+      ".meta/example.erl"
+    ]
+  },
+  "source": "Conversation with James Edward Gray II",
+  "source_url": "https://twitter.com/jeg2"
+}

erlang/accumulate/.exercism/metadata.json

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+{"track":"erlang","exercise":"accumulate","id":"c9819e2454fa472d881c797983106708","url":"https://exercism.org/tracks/erlang/exercises/accumulate","handle":"JBiason","is_requester":true,"auto_approve":false}

erlang/accumulate/HELP.md

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+# Help
+
+## Running the tests
+
+You can run the tests by running the following command from the exercise directory.
+
+```bash
+$ rebar3 eunit
+```
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/accumulate.erl` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Erlang track's documentation](https://exercism.org/docs/tracks/erlang)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+To get help if you're having trouble, you can use one of the following resources:
+
+- [Exercism related BEAM support channel on gitter](https://gitter.im/exercism/xerlang)
+- [Erlang Documentation](http://www.erlang.org/doc.html)
+- [Learn You Some Erlang for Great Good](http://learnyousomeerlang.com)
+- [StackOverflow](http://stackoverflow.com/)

erlang/accumulate/README.md

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+# Accumulate
+
+Welcome to Accumulate on Exercism's Erlang Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Implement the `accumulate` operation, which, given a collection and an
+operation to perform on each element of the collection, returns a new
+collection containing the result of applying that operation to each element of
+the input collection.
+
+Given the collection of numbers:
+
+- 1, 2, 3, 4, 5
+
+And the operation:
+
+- square a number (`x => x * x`)
+
+Your code should be able to produce the collection of squares:
+
+- 1, 4, 9, 16, 25
+
+Check out the test suite to see the expected function signature.
+
+## Restrictions
+
+Keep your hands off that collect/map/fmap/whatchamacallit functionality
+provided by your standard library!
+Solve this one yourself using other basic tools instead.
+
+## Source
+
+### Contributed to by
+
+- @adolfopa
+- @ErikSchierboom
+- @etrepum
+- @iHiD
+- @JordanAdams
+- @juhlig
+- @kytrinyx
+- @magthe
+- @NobbZ
+- @tmcgilchrist
+- @xymbol
+
+### Based on
+
+Conversation with James Edward Gray II - https://twitter.com/jeg2

erlang/accumulate/rebar.config

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+%% Erlang compiler options
+{erl_opts, [debug_info, warnings_as_errors]}.
+
+{deps, [{erl_exercism, "0.1.2"}]}.
+
+{dialyzer, [
+  {warnings, [underspecs, no_return]},
+  {get_warnings, true},
+  {plt_apps, top_level_deps}, % top_level_deps | all_deps
+  {plt_extra_apps, []},
+  {plt_location, local}, % local | "/my/file/name"
+  {plt_prefix, "rebar3"},
+  {base_plt_apps, [stdlib, kernel, crypto]},
+  {base_plt_location, global}, % global | "/my/file/name"
+  {base_plt_prefix, "rebar3"}
+]}.
+
+%% eunit:test(Tests)
+{eunit_tests, []}.
+%% Options for eunit:test(Tests, Opts)
+{eunit_opts, [verbose]}.
+
+%% == xref ==
+
+{xref_warnings, true}.
+
+%% xref checks to run
+{xref_checks, [undefined_function_calls, undefined_functions,
+  locals_not_used, exports_not_used,
+  deprecated_function_calls, deprecated_functions]}.

erlang/accumulate/src/accumulate.app.src

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+{application, accumulate,
+  [{description, "exercism.io - accumulate"},
+    {vsn, "0.0.0"},
+    {modules, []},
+    {registered, []},
+    {applications, [kernel,
+      stdlib]},
+    {env, []}
+  ]}.

erlang/accumulate/src/accumulate.erl

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+-module(accumulate).
+
+-export([accumulate/2]).
+
+accumulate(Fn, [H|T]) ->
+  [Fn(H) | accumulate(Fn, T)];
+accumulate(_Fn, []) ->
+  [].

erlang/accumulate/test/accumulate_tests.erl

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+-module(accumulate_tests).
+
+-include_lib("erl_exercism/include/exercism.hrl").
+-include_lib("eunit/include/eunit.hrl").
+
+accumulate_empty_list_test() ->
+  Fn = fun() -> ok end,
+  Ls = [],
+  ?assertEqual([], accumulate:accumulate(Fn, Ls)).
+
+accumulate_squares_test() ->
+  Fn = fun(Number) -> Number * Number end,
+  Ls = [1, 2, 3],
+  ?assertEqual([1, 4, 9], accumulate:accumulate(Fn, Ls)).
+
+accumulate_upcases_test() ->
+  Fn = fun(Word) -> string:to_upper(Word) end,
+  Ls = string:tokens("hello world", " "),
+  ?assertEqual(["HELLO", "WORLD"], accumulate:accumulate(Fn, Ls)).
+
+accumulate_reversed_strings_test() ->
+  Fn = fun(Word) -> lists:reverse(Word) end,
+  Ls = string:tokens("the quick brown fox etc", " "),
+  ?assertEqual(["eht", "kciuq", "nworb", "xof", "cte"], accumulate:accumulate(Fn, Ls)).
+
+accumulate_recursively_test() ->
+  Chars = string:tokens("a b c", " "),
+  Nums = string:tokens("1 2 3", " "),
+  Fn = fun(Char) -> [Char ++ Num || Num <- Nums] end,
+  ?assertEqual([["a1", "a2", "a3"], ["b1", "b2", "b3"], ["c1", "c2", "c3"]], accumulate:accumulate(Fn, Chars)).