list-ops-exercise: added new exercise. (#125)

config.json

@@ -382,6 +382,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 1
+      },
+      {
+        "slug": "list-ops",
+        "name": "List-Ops",
+        "uuid": "e7e3d67a-8c2b-49b7-9dc0-9c4d2677c7d0",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
       }
     ]
   },

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.

exercises/practice/list-ops/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "SimaDovakin"
+  ],
+  "files": {
+    "solution": [
+      "listOps.u"
+    ],
+    "test": [
+      "listOps.test.u"
+    ],
+    "example": [
+      ".meta/examples/listOps.example.u"
+    ]
+  },
+  "blurb": "Implement basic list operations."
+}

exercises/practice/list-ops/.meta/examples/listOps.example.u

@@ -0,0 +1,46 @@
+listOps.append : [a] -> [a] -> [a]
+listOps.append list1 list2 =
+  match list1 with
+    [] -> list2
+    x +: xs -> x +: listOps.append xs list2
+
+listOps.concat : [[a]] -> [a]
+listOps.concat nestedList =
+  listOps.foldl append [] nestedList
+
+listOps.filter : (a -> Boolean) -> [a] -> [a]
+listOps.filter predicate list =
+  match list with
+    [] -> []
+    x +: xs ->
+      match predicate x with
+        true -> x +: listOps.filter predicate xs
+        false -> listOps.filter predicate xs
+
+listOps.length : [a] -> Nat
+listOps.length list =
+  match list with
+    [] -> 0
+    x +: xs -> 1 + listOps.length xs
+
+listOps.map : (a -> b) -> [a] -> [b]
+listOps.map function list =
+  match list with
+    [] -> []
+    x +: xs -> function x +: listOps.map function xs
+
+listOps.foldl : (a -> b -> a) -> a -> [b] -> a
+listOps.foldl function initial list =
+  match list with
+    [] -> initial
+    x +: xs -> listOps.foldl function (function initial x) xs
+
+listOps.foldr : (a -> b -> a) -> a -> [b] -> a
+listOps.foldr function initial list =
+  listOps.foldl function initial (listOps.reverse list)
+
+listOps.reverse : [a] -> [a]
+listOps.reverse list =
+  match list with
+    [] -> []
+    x +: xs -> listOps.append (listOps.reverse xs) [x]

exercises/practice/list-ops/.meta/testAnnotation.json

@@ -0,0 +1,90 @@
+[
+  {
+    "name": "listOps.append.tests.ex1",
+    "test_code": "Test.expect ([] === (listOps.append [] []))\n    |> Test.label \"append entries to a list and return the new list - empty lists\""
+  },
+  {
+    "name": "listOps.append.tests.ex2",
+    "test_code": "Test.expect ([1, 2, 3, 4] === listOps.append [] [1, 2, 3, 4])\n    |> Test.label \"append entries to a list and return the new list - list to empty list\""
+  },
+  {
+    "name": "listOps.append.tests.ex3",
+    "test_code": "Test.expect ([1, 2, 3, 4] === listOps.append [1, 2, 3, 4] [])\n    |> Test.label \"append entries to a list and return the new list - empty list to list\""
+  },
+  {
+    "name": "listOps.append.tests.ex4",
+    "test_code": "Test.expect ([1, 2, 2, 3, 4, 5] === listOps.append [1, 2] [2, 3, 4, 5])\n    |> Test.label \"append entries to a list and return the new list - non-empty lists\""
+  },
+  {
+    "name": "listOps.concat.tests.ex1",
+    "test_code": "Test.expect ([] === listOps.concat [])\n    |> Test.label \"concatenate a list of lists - empty list\""
+  },
+  {
+    "name": "listOps.concat.tests.ex2",
+    "test_code": "Test.expect ([1, 2, 3, 4, 5, 6] === listOps.concat [[1, 2], [3], [], [4, 5, 6]])\n    |> Test.label \"concatenate a list of lists - list of lists\""
+  },
+  {
+    "name": "listOps.concat.tests.ex3",
+    "test_code": "Test.expect ([[1], [2], [3], [], [4, 5, 6]] === listOps.concat [[[1], [2]], [[3]], [[]], [[4, 5, 6]]])\n    |> Test.label \"concatenate a list of lists - list of nested lists\""
+  },
+  {
+    "name": "listOps.filter.tests.ex1",
+    "test_code": "Test.expect ([] === listOps.filter (x -> 1 == mod x 2) [])\n    |> Test.label \"filter list returning only values that satisfy the filter function - empty list\""
+  },
+  {
+    "name": "listOps.filter.tests.ex2",
+    "test_code": "Test.expect ([1, 3, 5] === listOps.filter (x -> 1 == mod x 2) [1, 2, 3, 5])\n    |> Test.label \"filter list returning only values that satisfy the filter function - non-empty list\""
+  },
+  {
+    "name": "listOps.foldl.tests.ex1",
+    "test_code": "use Nat *\n  Test.expect (2 == listOps.foldl (acc el -> el * acc) 2 [])\n    |> Test.label \"folds (reduces) the given list from the left with a function - empty list\""
+  },
+  {
+    "name": "listOps.foldl.tests.ex2",
+    "test_code": "use Nat +\n  Test.expect (15 == listOps.foldl (acc el -> el + acc) 5 [1, 2, 3, 4])\n    |> Test.label \"folds (reduces) the given list from the left with a function - direction independent function applied to non-empty list\""
+  },
+  {
+    "name": "listOps.foldl.tests.ex3",
+    "test_code": "use Float /\n  Test.expect (64.0 == listOps.foldl (acc el -> el / acc) 24.0 [1.0, 2.0, 3.0, 4.0])\n    |> Test.label \"folds (reduces) the given list from the left with a function - direction dependent function applied to non-empty list\""
+  },
+  {
+    "name": "listOps.foldr.tests.ex1",
+    "test_code": "use Nat *\n  Test.expect (2 == listOps.foldr (acc el -> el * acc) 2 [])\n    |> Test.label \"folds (reduces) the given list from the right with a function - empty list\""
+  },
+  {
+    "name": "listOps.foldr.tests.ex2",
+    "test_code": "use Nat +\n  Test.expect (15 == listOps.foldr (acc el -> el + acc) 5 [1, 2, 3, 4])\n    |> Test.label \"folds (reduces) the given list from the right with a function - direction independent function applied to non-empty list\""
+  },
+  {
+    "name": "listOps.foldr.tests.ex3",
+    "test_code": "use Float /\n  Test.expect (9.0 == listOps.foldr (acc el -> el / acc) 24.0 [1.0, 2.0, 3.0, 4.0])\n    |> Test.label \"folds (reduces) the given list from the right with a function - direction dependent function applied to non-empty list\""
+  },
+  {
+    "name": "listOps.length.tests.ex1",
+    "test_code": "Test.expect (0 == listOps.length [])\n    |> Test.label \"returns the length of a list - empty list\""
+  },
+  {
+    "name": "listOps.length.tests.ex2",
+    "test_code": "Test.expect (4 == listOps.length [1, 2, 3, 4])\n    |> Test.label \"returns the length of a list - non-empty list\""
+  },
+  {
+    "name": "listOps.map.tests.ex1",
+    "test_code": "Test.expect ([] === listOps.map (x -> x + 1) [])\n    |> Test.label \"return a list of elements whose values equal the list value transformed by the mapping function - empty list\""
+  },
+  {
+    "name": "listOps.map.tests.ex2",
+    "test_code": "Test.expect ([2, 4, 6, 8] === listOps.map (x -> x + 1) [1, 3, 5, 7])\n    |> Test.label \"return a list of elements whose values equal the list value transformed by the mapping function - non-empty list\""
+  },
+  {
+    "name": "listOps.reverse.tests.ex1",
+    "test_code": "Test.expect ([] === listOps.reverse [])\n    |> Test.label \"reverse the elements of the list - empty list\""
+  },
+  {
+    "name": "listOps.reverse.tests.ex2",
+    "test_code": "Test.expect ([7, 5, 3, 1] === listOps.reverse [1, 3, 5, 7])\n    |> Test.label \"reverse the elements of the list - non-empty list\""
+  },
+  {
+    "name": "listOps.reverse.tests.ex3",
+    "test_code": "Test.expect ([[4, 5, 6], [], [3], [1, 2]] === listOps.reverse [[1, 2], [3], [], [4, 5, 6]])\n    |> Test.label \"reverse the elements of the list - list of lists is not flattened\""
+  }
+]

exercises/practice/list-ops/.meta/testLoader.md

@@ -0,0 +1,9 @@
+# Testing transcript for list-ops exercise
+
+```ucm
+.> load ./listOps.u
+.> add
+.> load ./listOps.test.u
+.> add
+.> move.term listOps.tests tests
+```

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"
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+description = "return a list of elements whose values equal the list value transformed by the mapping function -> empty list"
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+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]
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+
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+
+[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
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+[8066003b-f2ff-437e-9103-66e6df474844]
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+
+[94231515-050e-4841-943d-d4488ab4ee30]
+description = "reverse the elements of the list -> empty list"
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+[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"