feat(list-ops): add exercise list-ops to vlang track (resolves #144)

config.json

@@ -113,6 +113,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "uuid": "c7b387ae-3ea2-40d2-9792-5f83d14f316e",
+        "slug": "list-ops",
+        "name": "List Ops",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 6
+      },
       {
         "uuid": "e9a9d0d1-1756-4be5-8fc8-bd2d2d52611c",
         "slug": "grains",

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 +1,9 @@
+{
+  "authors": ["m-charlton"],
+  "files": {
+    "solution": ["list-ops.v"],
+    "test": ["run_test.v"],
+    "example": [".meta/example.v"]
+  },
+  "blurb": "Implement basic list operations."
+}

exercises/practice/list-ops/.meta/example.v

@@ -0,0 +1,87 @@
+module main
+
+pub fn append[T](front []T, back []T) []T {
+	front_len := front.len
+
+	mut result := []T{len: front_len + back.len}
+
+	for i, element in front {
+		result[i] = element
+	}
+
+	for i, element in back {
+		result[front_len + i] = element
+	}
+
+	return result
+}
+
+pub fn concat[T](array [][]T) []T {
+	mut result_len := 0
+
+	for element in array {
+		result_len += element.len
+	}
+
+	mut result := []T{cap: result_len}
+
+	for element in array {
+		result = append(result, element)
+	}
+
+	return result
+}
+
+pub fn foldl[T, U](array []T, initial U, folder fn (acc U, e T) U) U {
+	mut result := initial
+
+	for element in array {
+		result = folder(result, element)
+	}
+
+	return result
+}
+
+pub fn foldr[T, U](array []T, initial U, folder fn (acc U, e T) U) U {
+	return foldl(reverse(array), initial, folder)
+}
+
+pub fn length[T](array []T) int {
+	return foldl[T, int](array, 0, fn [T](acc int, _ T) int {
+		return acc + 1
+	})
+}
+
+pub fn reverse[T](array []T) []T {
+	mut result := []T{cap: array.len}
+
+	for element in array {
+		result = append([element], result)
+	}
+
+	return result
+}
+
+pub fn filter[T](array []T, predicate fn (e T) bool) []T {
+	mut result := []T{cap: array.len}
+
+	for element in array {
+		if predicate(element) {
+			result = append(result, [element])
+		}
+	}
+
+	return result
+}
+
+// renamed 'map_of' as 'map' conflicts with V 'map' datatype
+
+pub fn map_of[T, U](array []T, mapper fn (e T) U) []U {
+	mut result := []U{cap: array.len}
+
+	for element in array {
+		result = append(result, [mapper(element)])
+	}
+
+	return result
+}

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"

exercises/practice/list-ops/list-ops.v

@@ -0,0 +1,27 @@
+module main
+
+pub fn append[T](front []T, back []T) []T {
+}
+
+pub fn concat[T](array [][]T) []T {
+}
+
+pub fn foldl[T, U](array []T, initial U, folder fn (acc U, e T) U) U {
+}
+
+pub fn foldr[T, U](array []T, initial U, folder fn (acc U, e T) U) U {
+}
+
+pub fn length[T](array []T) int {
+}
+
+pub fn reverse[T](array []T) []T {
+}
+
+pub fn filter[T](array []T, predicate fn (e T) bool) []T {
+}
+
+// renamed 'map_of' as 'map' conflicts with V 'map' datatype
+
+pub fn map_of[T, U](array []T, mapper fn (e T) U) []U {
+}