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skovsgaard's solution

to Anagram in the LFE Track

Published at Jul 13 2018 · 3 comments
Instructions
Test suite
Solution

Given a word and a list of possible anagrams, select the correct sublist.

Given "listen" and a list of candidates like "enlists" "google" "inlets" "banana" the program should return a list containing "inlets".


For installation and learning resources, refer to the exercism help page.

To run the provided tests, you will need make. Open a terminal window and run the following from the exercise directory:

make test

You should now be able to see the results of the test suite for the exercise.

Source

Inspired by the Extreme Startup game https://github.com/rchatley/extreme_startup

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

anagram-tests.lfe

(defmodule anagram-tests
  (behaviour ltest-unit)
  (export all))

(include-lib "ltest/include/ltest-macros.lfe")

(deftest no-matches
  (is-equal () (anagram:find "diaper" '("hello" "world" "zombies" "pants"))))

(deftest detect-simple-anagram
  (is-equal '("tan") (anagram:find "ant" '("tan" "stand" "at"))))

(deftest does-not-confuse-different-duplicates
  (is-equal () (anagram:find "galea" '("eagle"))))

(deftest eliminate-angram-subsets
  (is-equal () (anagram:find "good" '("dog" "goody"))))

(deftest detect-anagram
  (is-equal
    '("inlets")
    (anagram:find "listen" '("enlists" "google" "inlets" "banana"))))

(deftest multiple-anagrams
  (is-equal
    '("gallery" "regally" "largely")
    (anagram:find
      "allergy"
      '("gallery" "ballerina" "regally" "clergy" "largely" "leading"))))

(deftest case-insensitive-subject
  (is-equal
    '("carthorse")
    (anagram:find "Orchestra" '("cashregister" "carthorse" "radishes"))))

(deftest case-insensitive-candidate
  (is-equal
    '("Carthorse")
    (anagram:find "Orchestra" '("cashregister" "Carthorse" "radishes"))))

(deftest does-not-detect-a-word-as-its-own-anagram
  (is-equal
    '("cron")
    (anagram:find "corn" '("corn" "dark" "Corn" "rank" "CORN" "cron" "park"))))
(defmodule anagram
  (export (find 2)))

(defun find (word possibilities)
  (lists:filter
   (lambda (x) (!= x '()))
   (lc ((<- possibility possibilities))
     (if (and
	  (== (lists:sort (string:to_lower word))
	      (lists:sort (string:to_lower possibility)))
	  (!= word (string:to_lower possibility)))
       possibility
       '()))))

Community comments

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Avatar of yurrriq

There's no need to quote the empty list, ()

Consider "memoizing" (string:to_lower possibility)

Consider andalso instead of and to avoid unnecessary calculations

Consider folding the filter into the list comprehension I see what you're doing here.

Avatar of skovsgaard
skovsgaard
Solution Author
commented about 3 years ago

I'm not sure I understand andalso. Is it like short circuiting the and in Common Lisp? E.g. (and 'truthy 'values 'go 'here "Return something if they're all true")

Avatar of yurrriq

Yeah, most notably, for example, this wouldn't throw: (andalso 'true (throw 'never))

but this would (and 'true (throw 'never))

Same goes for orelse vs or.

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