From ce42dacae675b8b9074c400721d32dc4bf9424a9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A1s=20B=20Nagy?= <20251272+BNAndras@users.noreply.github.com> Date: Sun, 25 Feb 2024 23:35:24 -0800 Subject: [PATCH] Add list-ops --- config.json | 8 ++ .../practice/list-ops/.docs/instructions.md | 19 +++ exercises/practice/list-ops/.meta/config.json | 17 +++ .../practice/list-ops/.meta/example.coffee | 42 ++++++ exercises/practice/list-ops/.meta/tests.toml | 106 ++++++++++++++ exercises/practice/list-ops/list-ops.coffee | 18 +++ .../practice/list-ops/list-ops.spec.coffee | 132 ++++++++++++++++++ 7 files changed, 342 insertions(+) create mode 100644 exercises/practice/list-ops/.docs/instructions.md create mode 100644 exercises/practice/list-ops/.meta/config.json create mode 100644 exercises/practice/list-ops/.meta/example.coffee create mode 100644 exercises/practice/list-ops/.meta/tests.toml create mode 100644 exercises/practice/list-ops/list-ops.coffee create mode 100644 exercises/practice/list-ops/list-ops.spec.coffee diff --git a/config.json b/config.json index bf28e9c..72bfca4 100644 --- a/config.json +++ b/config.json @@ -510,6 +510,14 @@ "practices": [], "prerequisites": [], "difficulty": 2 + }, + { + "slug": "list-ops", + "name": "List Ops", + "uuid": "2f1a1b01-d8ae-46c7-a439-51923382d2cd", + "practices": [], + "prerequisites": [], + "difficulty": 2 } ] }, diff --git a/exercises/practice/list-ops/.docs/instructions.md b/exercises/practice/list-ops/.docs/instructions.md new file mode 100644 index 0000000..ebc5dff --- /dev/null +++ b/exercises/practice/list-ops/.docs/instructions.md @@ -0,0 +1,19 @@ +# Instructions + +Implement basic list operations. + +In functional languages list operations like `length`, `map`, and `reduce` are very common. +Implement a series of basic list operations, without using existing functions. + +The precise number and names of the operations to be implemented will be track dependent to avoid conflicts with existing names, but the general operations you will implement include: + +- `append` (_given two lists, add all items in the second list to the end of the first list_); +- `concatenate` (_given a series of lists, combine all items in all lists into one flattened list_); +- `filter` (_given a predicate and a list, return the list of all items for which `predicate(item)` is True_); +- `length` (_given a list, return the total number of items within it_); +- `map` (_given a function and a list, return the list of the results of applying `function(item)` on all items_); +- `foldl` (_given a function, a list, and initial accumulator, fold (reduce) each item into the accumulator from the left_); +- `foldr` (_given a function, a list, and an initial accumulator, fold (reduce) each item into the accumulator from the right_); +- `reverse` (_given a list, return a list with all the original items, but in reversed order_). + +Note, the ordering in which arguments are passed to the fold functions (`foldl`, `foldr`) is significant. diff --git a/exercises/practice/list-ops/.meta/config.json b/exercises/practice/list-ops/.meta/config.json new file mode 100644 index 0000000..fe4c437 --- /dev/null +++ b/exercises/practice/list-ops/.meta/config.json @@ -0,0 +1,17 @@ +{ + "authors": [ + "BNAndras" + ], + "files": { + "solution": [ + "list-ops.coffee" + ], + "test": [ + "list-ops.spec.coffee" + ], + "example": [ + ".meta/example.coffee" + ] + }, + "blurb": "Implement basic list operations." +} diff --git a/exercises/practice/list-ops/.meta/example.coffee b/exercises/practice/list-ops/.meta/example.coffee new file mode 100644 index 0000000..9990311 --- /dev/null +++ b/exercises/practice/list-ops/.meta/example.coffee @@ -0,0 +1,42 @@ +class ListOps + @append: (list1, list2) -> + @concat([list1, list2]) + + @concat: (lists) -> + results = [] + for list in lists + for elt in list + results.push elt + results + + @filter: (list, f) -> + (elt for elt in list when f(elt)) + + @mylength: (list) -> + fn = (acc, _) -> acc + 1 + @foldl(list, fn, 0) + + @map: (list, fn) -> + (fn(elt) for elt in list) + + @foldl: (list, fn, initial) -> + results = initial + for elt in list + results = fn(results, elt) + results + + @foldr: (list, fn, initial) -> + if list.length == 0 + initial + else + last = list.pop() + @foldr(list, fn, fn(initial, last)) + + @reverse: (list) -> + if list.length == 0 + list + else + start = list.length - 1 + (list[i] for i in [start..0]) + +module.exports = ListOps diff --git a/exercises/practice/list-ops/.meta/tests.toml b/exercises/practice/list-ops/.meta/tests.toml new file mode 100644 index 0000000..08b1edc --- /dev/null +++ b/exercises/practice/list-ops/.meta/tests.toml @@ -0,0 +1,106 @@ +# This is an auto-generated file. +# +# Regenerating this file via `configlet sync` will: +# - Recreate every `description` key/value pair +# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications +# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion) +# - Preserve any other key/value pair +# +# As user-added comments (using the # character) will be removed when this file +# is regenerated, comments can be added via a `comment` key. + +[485b9452-bf94-40f7-a3db-c3cf4850066a] +description = "append entries to a list and return the new list -> empty lists" + +[2c894696-b609-4569-b149-8672134d340a] +description = "append entries to a list and return the new list -> list to empty list" + +[e842efed-3bf6-4295-b371-4d67a4fdf19c] +description = "append entries to a list and return the new list -> empty list to list" + +[71dcf5eb-73ae-4a0e-b744-a52ee387922f] +description = "append entries to a list and return the new list -> non-empty lists" + +[28444355-201b-4af2-a2f6-5550227bde21] +description = "concatenate a list of lists -> empty list" + +[331451c1-9573-42a1-9869-2d06e3b389a9] +description = "concatenate a list of lists -> list of lists" + +[d6ecd72c-197f-40c3-89a4-aa1f45827e09] +description = "concatenate a list of lists -> list of nested lists" + +[0524fba8-3e0f-4531-ad2b-f7a43da86a16] +description = "filter list returning only values that satisfy the filter function -> empty list" + +[88494bd5-f520-4edb-8631-88e415b62d24] +description = "filter list returning only values that satisfy the filter function -> non-empty list" + +[1cf0b92d-8d96-41d5-9c21-7b3c37cb6aad] +description = "returns the length of a list -> empty list" + +[d7b8d2d9-2d16-44c4-9a19-6e5f237cb71e] +description = "returns the length of a list -> non-empty list" + +[c0bc8962-30e2-4bec-9ae4-668b8ecd75aa] +description = "return a list of elements whose values equal the list value transformed by the mapping function -> empty list" + +[11e71a95-e78b-4909-b8e4-60cdcaec0e91] +description = "return a list of elements whose values equal the list value transformed by the mapping function -> non-empty list" + +[613b20b7-1873-4070-a3a6-70ae5f50d7cc] +description = "folds (reduces) the given list from the left with a function -> empty list" +include = false + +[e56df3eb-9405-416a-b13a-aabb4c3b5194] +description = "folds (reduces) the given list from the left with a function -> direction independent function applied to non-empty list" +include = false + +[d2cf5644-aee1-4dfc-9b88-06896676fe27] +description = "folds (reduces) the given list from the left with a function -> direction dependent function applied to non-empty list" +include = false + +[36549237-f765-4a4c-bfd9-5d3a8f7b07d2] +description = "folds (reduces) the given list from the left with a function -> empty list" +reimplements = "613b20b7-1873-4070-a3a6-70ae5f50d7cc" + +[7a626a3c-03ec-42bc-9840-53f280e13067] +description = "folds (reduces) the given list from the left with a function -> direction independent function applied to non-empty list" +reimplements = "e56df3eb-9405-416a-b13a-aabb4c3b5194" + +[d7fcad99-e88e-40e1-a539-4c519681f390] +description = "folds (reduces) the given list from the left with a function -> direction dependent function applied to non-empty list" +reimplements = "d2cf5644-aee1-4dfc-9b88-06896676fe27" + +[aeb576b9-118e-4a57-a451-db49fac20fdc] +description = "folds (reduces) the given list from the right with a function -> empty list" +include = false + +[c4b64e58-313e-4c47-9c68-7764964efb8e] +description = "folds (reduces) the given list from the right with a function -> direction independent function applied to non-empty list" +include = false + +[be396a53-c074-4db3-8dd6-f7ed003cce7c] +description = "folds (reduces) the given list from the right with a function -> direction dependent function applied to non-empty list" +include = false + +[17214edb-20ba-42fc-bda8-000a5ab525b0] +description = "folds (reduces) the given list from the right with a function -> empty list" +reimplements = "aeb576b9-118e-4a57-a451-db49fac20fdc" + +[e1c64db7-9253-4a3d-a7c4-5273b9e2a1bd] +description = "folds (reduces) the given list from the right with a function -> direction independent function applied to non-empty list" +reimplements = "c4b64e58-313e-4c47-9c68-7764964efb8e" + +[8066003b-f2ff-437e-9103-66e6df474844] +description = "folds (reduces) the given list from the right with a function -> direction dependent function applied to non-empty list" +reimplements = "be396a53-c074-4db3-8dd6-f7ed003cce7c" + +[94231515-050e-4841-943d-d4488ab4ee30] +description = "reverse the elements of the list -> empty list" + +[fcc03d1e-42e0-4712-b689-d54ad761f360] +description = "reverse the elements of the list -> non-empty list" + +[40872990-b5b8-4cb8-9085-d91fc0d05d26] +description = "reverse the elements of the list -> list of lists is not flattened" diff --git a/exercises/practice/list-ops/list-ops.coffee b/exercises/practice/list-ops/list-ops.coffee new file mode 100644 index 0000000..c9b176f --- /dev/null +++ b/exercises/practice/list-ops/list-ops.coffee @@ -0,0 +1,18 @@ +class ListOps + @append: (list1, list2) -> + + @concat: (lists) -> + + @filter: (list, f) -> + + @mylength: (list) -> + + @map: (list, fn) -> + + @foldl: (list, fn, initial) -> + + @foldr: (list, fn, initial) -> + + @reverse: (list) -> + +module.exports = ListOps diff --git a/exercises/practice/list-ops/list-ops.spec.coffee b/exercises/practice/list-ops/list-ops.spec.coffee new file mode 100644 index 0000000..0916662 --- /dev/null +++ b/exercises/practice/list-ops/list-ops.spec.coffee @@ -0,0 +1,132 @@ +ListOps = require './list-ops' + +describe "List Ops", -> + it "append empty lists", -> + list1 = [] + list2 = [] + result = ListOps.append list1, list2 + expect(result).toEqual [] + + xit "append -> list to empty list", -> + list1 = [] + list2 = [1, 2, 3, 4] + result = ListOps.append list1, list2 + expect(result).toEqual [1, 2, 3, 4] + + xit "append -> empty list to list", -> + list1 = [1, 2, 3, 4] + list2 = [] + result = ListOps.append list1, list2 + expect(result).toEqual [1, 2, 3, 4] + + xit "append -> non-empty lists", -> + list1 = [1, 2] + list2 = [2, 3, 4, 5] + result = ListOps.append list1, list2 + expect(result).toEqual [1, 2, 2, 3, 4, 5] + + xit "concatenate -> empty list", -> + lists = [] + result = ListOps.concat lists + expect(result).toEqual [] + + xit "concatenate -> list of lists", -> + lists = [[1, 2], [3], [], [4, 5, 6]] + result = ListOps.concat lists + expect(result).toEqual [1, 2, 3, 4, 5, 6] + + xit "concatenate -> list of nested lists", -> + lists = [[[1], [2]], [[3]], [[]], [[4, 5, 6]]] + result = ListOps.concat lists + expect(result).toEqual [[1], [2], [3], [], [4, 5, 6]] + + xit "filter -> empty list", -> + list = [] + fn = (x) -> x % 2 == 1 + result = ListOps.filter list, fn + expect(result).toEqual [] + + xit "filter -> non-empty list", -> + list = [1, 2, 3, 5] + fn = (x) -> x % 2 == 1 + result = ListOps.filter list, fn + expect(result).toEqual [1, 3, 5] + + xit "length -> empty list", -> + list = [] + result = ListOps.mylength list + expect(result).toEqual 0 + + xit "length -> non-empty list", -> + list = [1, 2, 3, 4] + result = ListOps.mylength list + expect(result).toEqual 4 + + xit "map -> empty list", -> + list = [] + fn = (x) -> x + 1 + result = ListOps.map list, fn + expect(result).toEqual [] + + xit "map -> non-empty list", -> + list = [1, 3, 5, 7] + fn = (x) -> x + 1 + result = ListOps.map list, fn + expect(result).toEqual [2, 4, 6, 8] + + xit "fold left -> empty list", -> + list = [] + initial = 2 + fn = (acc, el) -> el * acc + result = ListOps.foldl list, fn, initial + expect(result).toEqual 2 + + xit "fold left -> direction independent function applied to non-empty list", -> + list = [1, 2, 3, 4] + initial = 5 + fn = (acc, el) -> el + acc + result = ListOps.foldl list, fn, initial + expect(result).toEqual 15 + + xit "fold left -> direction dependent function applied to non-empty list", -> + list = [1, 2, 3, 4] + initial = 24 + fn = (acc, el) -> el / acc + result = ListOps.foldl list, fn, initial + expect(result).toEqual 64 + + xit "fold right -> empty list", -> + list = [] + initial = 2 + fn = (acc, el) -> el * acc + result = ListOps.foldr list, fn, initial + expect(result).toEqual 2 + + xit "fold right -> direction independent function applied to non-empty list", -> + list = [1, 2, 3, 4] + initial = 5 + fn = (acc, el) -> el + acc + result = ListOps.foldr list, fn, initial + expect(result).toEqual 15 + + xit "fold right -> direction dependent function applied to non-empty list", -> + list = [1, 2, 3, 4] + initial = 24 + fn = (acc, el) -> el / acc + result = ListOps.foldr list, fn, initial + expect(result).toEqual 9 + + xit "reverse -> empty list", -> + list = [] + result = ListOps.reverse list + expect(result).toEqual [] + + xit "reverse -> non-empty list", -> + list = [1, 3, 5, 7] + result = ListOps.reverse list + expect(result).toEqual [7, 5, 3, 1] + + xit "reverse -> list of lists is not flattened", -> + list = [[1, 2], [3], [], [4, 5, 6]] + result = ListOps.reverse list + expect(result).toEqual [[4, 5, 6], [], [3], [1, 2]]