From 79ff1db97c73479910d85eda2c36af2b3ece1ee9 Mon Sep 17 00:00:00 2001 From: Adrien LUDWIG <42720099+Adrien-LUDWIG@users.noreply.github.com> Date: Tue, 31 Oct 2023 15:32:48 +0100 Subject: [PATCH] Add strain exercise (#297) (#306) * Add generated files for new exercise strain * Implement predicates in strain tests * Add strain example * Fix shadowing of the list built-in * Avoid repetition in tests * Use char=? instead of equal? --- config.json | 8 ++ .../practice/strain/.docs/instructions.md | 29 +++++++ exercises/practice/strain/.meta/config.json | 19 +++++ exercises/practice/strain/.meta/example.rkt | 11 +++ exercises/practice/strain/.meta/tests.toml | 52 ++++++++++++ exercises/practice/strain/strain-test.rkt | 80 +++++++++++++++++++ exercises/practice/strain/strain.rkt | 9 +++ 7 files changed, 208 insertions(+) create mode 100644 exercises/practice/strain/.docs/instructions.md create mode 100644 exercises/practice/strain/.meta/config.json create mode 100644 exercises/practice/strain/.meta/example.rkt create mode 100644 exercises/practice/strain/.meta/tests.toml create mode 100644 exercises/practice/strain/strain-test.rkt create mode 100644 exercises/practice/strain/strain.rkt diff --git a/config.json b/config.json index 7279cc72..f0b648f1 100644 --- a/config.json +++ b/config.json @@ -519,6 +519,14 @@ "prerequisites": [], "difficulty": 1 }, + { + "slug": "strain", + "name": "Strain", + "uuid": "f3c6fea7-f69e-4cc5-b71f-0d34204623a7", + "practices": [], + "prerequisites": [], + "difficulty": 2 + }, { "slug": "darts", "name": "Darts", diff --git a/exercises/practice/strain/.docs/instructions.md b/exercises/practice/strain/.docs/instructions.md new file mode 100644 index 00000000..3469ae65 --- /dev/null +++ b/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. diff --git a/exercises/practice/strain/.meta/config.json b/exercises/practice/strain/.meta/config.json new file mode 100644 index 00000000..f20f374a --- /dev/null +++ b/exercises/practice/strain/.meta/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "Adrien-LUDWIG" + ], + "files": { + "solution": [ + "strain.rkt" + ], + "test": [ + "strain-test.rkt" + ], + "example": [ + ".meta/example.rkt" + ] + }, + "blurb": "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.", + "source": "Conversation with James Edward Gray II", + "source_url": "http://graysoftinc.com/" +} diff --git a/exercises/practice/strain/.meta/example.rkt b/exercises/practice/strain/.meta/example.rkt new file mode 100644 index 00000000..ba2345cb --- /dev/null +++ b/exercises/practice/strain/.meta/example.rkt @@ -0,0 +1,11 @@ +#lang racket + +(provide keep discard) + +(define (keep lst predicate) + (for/list ([value lst] + #:when (predicate value)) + value)) + +(define (discard lst predicate) + (keep lst (negate predicate))) diff --git a/exercises/practice/strain/.meta/tests.toml b/exercises/practice/strain/.meta/tests.toml new file mode 100644 index 00000000..3a617b4a --- /dev/null +++ b/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" diff --git a/exercises/practice/strain/strain-test.rkt b/exercises/practice/strain/strain-test.rkt new file mode 100644 index 00000000..4c4571e0 --- /dev/null +++ b/exercises/practice/strain/strain-test.rkt @@ -0,0 +1,80 @@ +#lang racket/base + +(require "strain.rkt") + +(module+ test + (require rackunit rackunit/text-ui) + + (define (always-true _) #t) + + (define (always-false _) #f) + + (define (contains-5? lst) (member 5 lst)) + + (define (starts-with-z? str) (char=? (string-ref str 0) #\z)) + + (define suite + (test-suite + "strain tests" + + (test-equal? "keep on empty list returns empty list" + (keep '() always-true) + '()) + + (test-equal? "keeps everything" + (keep '(1 3 5) always-true) + '(1 3 5)) + + (test-equal? "keeps nothing" + (keep '(1 3 5) always-false) + '()) + + (test-equal? "keeps first and last" + (keep '(1 2 3) odd?) + '(1 3)) + + (test-equal? "keeps neither first nor last" + (keep '(1 2 3) even?) + '(2)) + + (test-equal? "keeps strings" + (keep '("apple" "zebra" "banana" "zombies" "cherimoya" "zealot") + starts-with-z?) + '("zebra" "zombies" "zealot")) + + (test-equal? "keeps lists" + (keep (list '(1 2 3) '(5 5 5) '(5 1 2) '(2 1 2) '(1 5 2) '(2 2 1) '(1 2 5)) + contains-5?) + (list '(5 5 5) '(5 1 2) '(1 5 2) '(1 2 5))) + + (test-equal? "discard on empty list returns empty list" + (discard '() always-true) + '()) + + (test-equal? "discards everything" + (discard '(1 3 5) always-true) + '()) + + (test-equal? "discards nothing" + (discard '(1 3 5) always-false) + '(1 3 5)) + + (test-equal? "discards first and last" + (discard '(1 2 3) odd?) + '(2)) + + (test-equal? "discards neither first nor last" + (discard '(1 2 3) even?) + '(1 3)) + + (test-equal? "discards strings" + (discard '("apple" "zebra" "banana" "zombies" "cherimoya" "zealot") + starts-with-z?) + '("apple" "banana" "cherimoya")) + + (test-equal? "discards lists" + (discard (list '(1 2 3) '(5 5 5) '(5 1 2) '(2 1 2) '(1 5 2) '(2 2 1) '(1 2 5)) + contains-5?) + (list '(1 2 3) '(2 1 2) '(2 2 1))))) + + (run-tests suite)) diff --git a/exercises/practice/strain/strain.rkt b/exercises/practice/strain/strain.rkt new file mode 100644 index 00000000..dc38d64e --- /dev/null +++ b/exercises/practice/strain/strain.rkt @@ -0,0 +1,9 @@ +#lang racket + +(provide keep discard) + +(define (keep lst predicate) + (error "Not implemented yet")) + +(define (discard lst predicate) + (error "Not implemented yet"))