change strain to use generics

config.json

@@ -710,7 +710,7 @@
         "uuid": "7fbb0d9d-71d1-4654-8ca0-bb07ddbe6cb5",
         "practices": [],
         "prerequisites": [],
-        "difficulty": 2,
+        "difficulty": 4,
         "topics": [
           "arrays",
           "filtering",

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

@@ -12,7 +12,8 @@
     "robphoenix",
     "sebito91",
     "soniakeys",
-    "eklatzer"
+    "eklatzer",
+    "junedev"
   ],
   "files": {
     "solution": [

exercises/practice/strain/.meta/example.go

@@ -1,43 +1,25 @@
 package strain
 
-type Ints []int
+func Keep[T any](list []T, fn func(T) bool) []T {
+	result := []T{}
 
-func (s Ints) Keep(f func(int) bool) (r Ints) {
-	for _, e := range s {
-		if f(e) {
-			r = append(r, e)
+	for _, entry := range list {
+		if fn(entry) {
+			result = append(result, entry)
 		}
 	}
-	return
-}
 
-func (s Ints) Discard(f func(int) bool) (r Ints) {
-	for _, e := range s {
-		if !f(e) {
-			r = append(r, e)
-		}
-	}
-	return
+	return result
 }
 
-type Strings []string
+func Discard[T any](list []T, fn func(T) bool) []T {
+	result := []T{}
 
-func (s Strings) Keep(f func(string) bool) (r Strings) {
-	for _, e := range s {
-		if f(e) {
-			r = append(r, e)
+	for _, entry := range list {
+		if !fn(entry) {
+			result = append(result, entry)
 		}
 	}
-	return
-}
 
-type Lists [][]int
-
-func (s Lists) Keep(f func([]int) bool) (r Lists) {
-	for _, e := range s {
-		if f(e) {
-			r = append(r, e)
-		}
-	}
-	return
+	return result
 }

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/strain.go

@@ -1,21 +1,7 @@
 package strain
 
-type Ints []int
-type Lists [][]int
-type Strings []string
+// Implement the "Keep" and "Discard" function in this file.
 
-func (i Ints) Keep(filter func(int) bool) Ints {
-	panic("Please implement the Keep function")
-}
-
-func (i Ints) Discard(filter func(int) bool) Ints {
-	panic("Please implement the Discard function")
-}
-
-func (l Lists) Keep(filter func([]int) bool) Lists {
-	panic("Please implement the Keep function")
-}
-
-func (s Strings) Keep(filter func(string) bool) Strings {
-	panic("Please implement the Keep function")
-}
+// You will need typed parameters (aka "Generics") to solve this exercise.
+// They are not part of the Exercism syllabus yet but you can learn about
+// them here: https://go.dev/tour/generics/1