add accumulate exercise (#407)

config.json

@@ -846,6 +846,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 5
+      },
+      {
+        "slug": "accumulate",
+        "name": "Accumulate",
+        "uuid": "093463bf-e8df-4dd9-b6e3-b5ec007cb781",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
       }
     ]
   },

exercises/practice/accumulate/.docs/instructions.md

@@ -0,0 +1,22 @@
+# Instructions
+
+Implement the `accumulate` operation, which, given a collection and an operation to perform on each element of the collection, returns a new collection containing the result of applying that operation to each element of the input collection.
+
+Given the collection of numbers:
+
+- 1, 2, 3, 4, 5
+
+And the operation:
+
+- square a number (`x => x * x`)
+
+Your code should be able to produce the collection of squares:
+
+- 1, 4, 9, 16, 25
+
+Check out the test suite to see the expected function signature.
+
+## Restrictions
+
+Keep your hands off that collect/map/fmap/whatchamacallit functionality provided by your standard library!
+Solve this one yourself using other basic tools instead.

exercises/practice/accumulate/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "kmarker1101"
+  ],
+  "files": {
+    "solution": [
+      "accumulate.el"
+    ],
+    "test": [
+      "accumulate-test.el"
+    ],
+    "example": [
+      ".meta/example.el"
+    ]
+  },
+  "blurb": "Implement the `accumulate` operation, which, given a collection and an operation to perform on each element of the collection, returns a new collection containing the result of applying that operation to each element of the input collection.",
+  "source": "Conversation with James Edward Gray II",
+  "source_url": "http://graysoftinc.com/"
+}

exercises/practice/accumulate/.meta/example.el

@@ -0,0 +1,15 @@
+;;; accumulate.el --- Accumulate (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(defun accumulate (lst op)
+  (cond
+   ((null lst) lst)
+   (t (cons (funcall op (car lst)) (accumulate (cdr lst) op)))))
+
+
+(provide 'accumulate)
+;;; accumulate.el ends here

exercises/practice/accumulate/.meta/tests.toml

@@ -0,0 +1,30 @@
+# 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.
+
+[64d97c14-36dd-44a8-9621-2cecebd6ed23]
+description = "accumulate empty"
+
+[00008ed2-4651-4929-8c08-8b4dbd70872e]
+description = "accumulate squares"
+
+[551016da-4396-4cae-b0ec-4c3a1a264125]
+description = "accumulate upcases"
+
+[cdf95597-b6ec-4eac-a838-3480d13d0d05]
+description = "accumulate reversed strings"
+
+[bee8e9b6-b16f-4cd2-be3b-ccf7457e50bb]
+description = "accumulate recursively"
+include = false
+
+[0b357334-4cad-49e1-a741-425202edfc7c]
+description = "accumulate recursively"
+reimplements = "bee8e9b6-b16f-4cd2-be3b-ccf7457e50bb"

exercises/practice/accumulate/accumulate-test.el

@@ -0,0 +1,43 @@
+;;; accumulate-test.el --- Accumulate (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(load-file "accumulate.el")
+(declare-function accumulate "accumulate.el" (lst op))
+
+
+(ert-deftest accumulate-empty ()
+  (let ((result (accumulate '() (lambda (x) (* x x)))))
+    (should (equal result '()))))
+
+
+(ert-deftest accumulate-square ()
+  (let ((result (accumulate '(1 2 3 4) (lambda (x) (* x x)))))
+    (should (equal result '(1 4 9 16)))))
+
+
+(ert-deftest accumulate-upcases ()
+  (let ((result (accumulate '("Hello" "world") 'upcase)))
+    (should (equal result '("HELLO" "WORLD")))))
+
+
+(ert-deftest accumulate-reversed-strings ()
+  (let ((result (accumulate '("the" "quick" "brown" "fox" "etc") (lambda (x) (apply #'string (reverse (string-to-list x)))))))
+    (should (equal result '("eht" "kciuq" "nworb" "xof" "cte")))))
+
+
+(ert-deftest accumulate-recursively ()
+  (let* ((inner-list '("1" "2" "3"))
+         (result (accumulate '("a" "b" "c")
+                             (lambda (x)
+                               (mapcar (lambda (y) (concat x y)) inner-list)))))
+    (should (equal result '(("a1" "a2" "a3")
+                            ("b1" "b2" "b3")
+                            ("c1" "c2" "c3"))))))
+
+
+(provide 'accumulate-test)
+;;; accumulate-test.el ends here

exercises/practice/accumulate/accumulate.el

@@ -0,0 +1,13 @@
+;;; accumulate.el --- Accumulate (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(defun accumulate (lst op)
+  (error "Delete this S-Expression and write your own implementation"))
+
+
+(provide 'accumulate)
+;;; accumulate.el ends here