Implement exercise 'strain'

config.json

@@ -260,6 +260,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "strain",
+        "name": "Strain",
+        "uuid": "1306a71c-5ddb-4421-a119-c4b5f2f38efe",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "triangle",
         "name": "Triangle",

config.yaml

@@ -239,6 +239,13 @@ exercises:
     prerequisites: []
     difficulty: 2
 
+  - slug: strain
+    name: Strain
+    uuid: 1306a71c-5ddb-4421-a119-c4b5f2f38efe
+    practices: []
+    prerequisites: []
+    difficulty: 2
+
   - slug: triangle
     name: Triangle
     uuid: 494f403b-3bd7-47f1-a866-d07e9faea677

exercises/practice/strain/.docs/instructions.md

@@ -0,0 +1,29 @@
+# Instructions
+
+Implement the `keep` and `discard` operation on collections.
+Given a collection and a predicate on the collection's elements, `keep` returns a new collection containing those elements where the predicate is true, while `discard` returns a new collection containing those elements where the predicate is false.
+
+For example, given the collection of numbers:
+
+- 1, 2, 3, 4, 5
+
+And the predicate:
+
+- is the number even?
+
+Then your keep operation should produce:
+
+- 2, 4
+
+While your discard operation should produce:
+
+- 1, 3, 5
+
+Note that the union of keep and discard is all the elements.
+
+The functions may be called `keep` and `discard`, or they may need different names in order to not clash with existing functions or concepts in your language.
+
+## Restrictions
+
+Keep your hands off that filter/reject/whatchamacallit functionality provided by your standard library!
+Solve this one yourself using other basic tools instead.

exercises/practice/strain/.meta/.yamlscript/exercise.mk

@@ -0,0 +1 @@
+YS_VERSION := 0.1.75

exercises/practice/strain/.meta/Makefile

@@ -0,0 +1,28 @@
+SHELL := bash
+
+BASE := $(shell pwd)
+
+export YS_VERSION := 0.1.79
+
+YS_LOCAL_PREFIX := ../../../../.local/v$(YS_VERSION)
+
+YS_LOCAL_BIN := $(YS_LOCAL_PREFIX)/bin
+
+YS_BIN := $(YS_LOCAL_BIN)/ys-$(YS_VERSION)
+
+TEST_FILE ?= $(wildcard *-test.ys)
+
+
+export PATH := $(YS_LOCAL_BIN):$(PATH)
+
+export YSPATH := $(BASE)
+
+
+default:
+
+test: $(YS_BIN)
+	prove -v $(TEST_FILE)
+
+$(YS_BIN):
+	curl -s https://yamlscript.org/install | \
+	  BIN=1 VERSION=$(YS_VERSION) PREFIX=$(YS_LOCAL_PREFIX) bash >/dev/null

exercises/practice/strain/.meta/config.json

@@ -0,0 +1,23 @@
+{
+  "authors": [
+    "ingydotnet"
+  ],
+  "files": {
+    "solution": [
+      "strain.ys"
+    ],
+    "test": [
+      "strain-test.ys",
+      "GNUmakefile",
+      "Makefile",
+      ".yamlscript/exercise.mk",
+      ".yamlscript/exercism-ys-installer"
+    ],
+    "example": [
+      ".meta/strain.ys"
+    ]
+  },
+  "blurb": "Implement the `keep` and `discard` operation on collections.",
+  "source": "Conversation with James Edward Gray II",
+  "source_url": "http://graysoftinc.com/"
+}

exercises/practice/strain/.meta/strain-test.ys

@@ -0,0 +1,125 @@
+#!/usr/bin/env ys-0
+
+require ys::taptest: :all
+
+use: strain
+
+test::
+- name: Keep on empty list returns empty list
+  code: 'keep([] "fn([x] true)")'
+  want: []
+  uuid: 26af8c32-ba6a-4eb3-aa0a-ebd8f136e003
+
+- name: Keeps everything
+  code: keep([1 3 5] "fn(x):\ true")
+  want:
+  - 1
+  - 3
+  - 5
+  uuid: f535cb4d-e99b-472a-bd52-9fa0ffccf454
+
+- name: Keeps nothing
+  code: keep([1 3 5] "fn(x):\ false")
+  want: []
+  uuid: 950b8e8e-f628-42a8-85e2-9b30f09cde38
+
+- name: Keeps first and last
+  code: keep([1 2 3] "fn(x):\ (x % 2) == 1")
+  want:
+  - 1
+  - 3
+  uuid: 92694259-6e76-470c-af87-156bdf75018a
+
+- name: Keeps neither first nor last
+  code: keep([1 2 3] "fn(x):\ (x % 2) == 0")
+  want:
+  - 2
+  uuid: 938f7867-bfc7-449e-a21b-7b00cbb56994
+
+- name: Keeps strings
+  code: keep(
+          qw(apple zebra banana zombies cherimoya zealot)
+          "fn(x):\ starts?(x, 'z')")
+  want:
+  - zebra
+  - zombies
+  - zealot
+  uuid: 8908e351-4437-4d2b-a0f7-770811e48816
+
+- name: Keeps lists
+  code: keep(
+          [[1 2 3] [5 5 5] [5 1 2] [2 1 2] [1 5 2] [2 2 1] [1 2 5]]
+          "fn(x):\ has?(x, 5)")
+  want:
+  - - 5
+    - 5
+    - 5
+  - - 5
+    - 1
+    - 2
+  - - 1
+    - 5
+    - 2
+  - - 1
+    - 2
+    - 5
+  uuid: 2728036b-102a-4f1e-a3ef-eac6160d876a
+
+- name: Discard on empty list returns empty list
+  code: discard([] "fn(x):\ true")
+  want: []
+  uuid: ef16beb9-8d84-451a-996a-14e80607fce6
+
+- name: Discards everything
+  code: discard([1 3 5] "fn(x):\ true")
+  want: []
+  uuid: 2f42f9bc-8e06-4afe-a222-051b5d8cd12a
+
+- name: Discards nothing
+  code: discard([1 3 5] "fn(x):\ false")
+  want:
+  - 1
+  - 3
+  - 5
+  uuid: ca990fdd-08c2-4f95-aa50-e0f5e1d6802b
+
+- name: Discards first and last
+  code: discard([1 2 3] "fn(x):\ (x % 2) == 1")
+  want:
+  - 2
+  uuid: 71595dae-d283-48ca-a52b-45fa96819d2f
+
+- name: Discards neither first nor last
+  code: discard([1 2 3] "fn(x):\ (x % 2) == 0")
+  want:
+  - 1
+  - 3
+  uuid: ae141f79-f86d-4567-b407-919eaca0f3dd
+
+- name: Discards strings
+  code: discard(
+          qw(apple zebra banana zombies cherimoya zealot)
+          "fn(x):\ starts?(x, 'z')")
+  want:
+  - apple
+  - banana
+  - cherimoya
+  uuid: daf25b36-a59f-4f29-bcfe-302eb4e43609
+
+- name: Discards lists
+  code: discard(
+          [[1 2 3] [5 5 5] [5 1 2] [2 1 2] [1 5 2] [2 2 1] [1 2 5]]
+          "fn(x):\ has?(x, 5)")
+  want:
+  - - 1
+    - 2
+    - 3
+  - - 2
+    - 1
+    - 2
+  - - 2
+    - 2
+    - 1
+  uuid: a38d03f9-95ad-4459-80d1-48e937e4acaf
+
+done: 14

exercises/practice/strain/.meta/strain.ys

@@ -0,0 +1,15 @@
+!yamlscript/v0
+
+defn keep(list predicate):
+  filter eval(predicate): list
+
+defn discard(list predicate):
+  remove eval(predicate): list
+
+# XXX: eval targeted to be in ys::std on 0.1.80
+defn eval(code):
+  str("!yamlscript/v0\n$code"):
+    .ys/compile()
+    .replace(/(?s)^\(\+\+\+ (.*)\)$/ '$1')
+    .read-string()
+    .clojure::core/eval()

exercises/practice/strain/.meta/tests.toml

@@ -0,0 +1,52 @@
+# 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.
+
+[26af8c32-ba6a-4eb3-aa0a-ebd8f136e003]
+description = "keep on empty list returns empty list"
+
+[f535cb4d-e99b-472a-bd52-9fa0ffccf454]
+description = "keeps everything"
+
+[950b8e8e-f628-42a8-85e2-9b30f09cde38]
+description = "keeps nothing"
+
+[92694259-6e76-470c-af87-156bdf75018a]
+description = "keeps first and last"
+
+[938f7867-bfc7-449e-a21b-7b00cbb56994]
+description = "keeps neither first nor last"
+
+[8908e351-4437-4d2b-a0f7-770811e48816]
+description = "keeps strings"
+
+[2728036b-102a-4f1e-a3ef-eac6160d876a]
+description = "keeps lists"
+
+[ef16beb9-8d84-451a-996a-14e80607fce6]
+description = "discard on empty list returns empty list"
+
+[2f42f9bc-8e06-4afe-a222-051b5d8cd12a]
+description = "discards everything"
+
+[ca990fdd-08c2-4f95-aa50-e0f5e1d6802b]
+description = "discards nothing"
+
+[71595dae-d283-48ca-a52b-45fa96819d2f]
+description = "discards first and last"
+
+[ae141f79-f86d-4567-b407-919eaca0f3dd]
+description = "discards neither first nor last"
+
+[daf25b36-a59f-4f29-bcfe-302eb4e43609]
+description = "discards strings"
+
+[a38d03f9-95ad-4459-80d1-48e937e4acaf]
+description = "discards lists"

exercises/practice/strain/.yamlscript/exercise.mk

@@ -0,0 +1 @@
+YS_VERSION := 0.1.75