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paulfioravanti's solution

to Anagram in the Elm Track

Published at Jun 27 2019 · 0 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".

Elm Installation

Refer to the Installing Elm page for information about installing elm.

Writing the Code

The first time you start an exercise, you'll need to ensure you have the appropriate dependencies installed. Thankfully, Elm makes that easy for you and will install dependencies when you try to run tests or build the code.

Execute the tests with:

$ elm-test

Automatically run tests again when you save changes:

$ elm-test --watch

As you work your way through the test suite, be sure to remove the skip <| calls from each test until you get them all passing!

Source

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

Submitting Incomplete Solutions

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

Tests.elm

module Tests exposing (tests)

import Anagram exposing (detect)
import Expect
import Test exposing (..)


tests : Test
tests =
    describe "Anagram"
        [ test "no matches" <|
            \() ->
                Expect.equal []
                    (detect "diaper" [ "hello", "world", "zombies", "pants" ])
        , skip <|
            test "detects simple anagram" <|
                \() ->
                    Expect.equal [ "tan" ]
                        (detect "ant" [ "tan", "stand", "at" ])
        , skip <|
            test "does not detect false positives" <|
                \() ->
                    Expect.equal []
                        (detect "galea" [ "eagle" ])
        , skip <|
            test "detects multiple anagrams" <|
                \() ->
                    Expect.equal [ "stream", "maters" ]
                        (detect "master" [ "stream", "pigeon", "maters" ])
        , skip <|
            test "does not detect anagram subsets" <|
                \() ->
                    Expect.equal []
                        (detect "good" [ "dog", "goody" ])
        , skip <|
            test "detects anagram" <|
                \() ->
                    Expect.equal [ "inlets" ]
                        (detect "listen" [ "enlists", "google", "inlets", "banana" ])
        , skip <|
            test "detects even more anagrams" <|
                \() ->
                    Expect.equal [ "gallery", "regally", "largely" ]
                        (detect "allergy" [ "gallery", "ballerina", "regally", "clergy", "largely", "leading" ])
        , skip <|
            test "does not detect indentical words" <|
                \() ->
                    Expect.equal [ "cron" ]
                        (detect "corn" [ "corn", "dark", "Corn", "rank", "CORN", "cron", "park" ])
        , skip <|
            test "does not detect non-anagrams with identical checksum" <|
                \() ->
                    Expect.equal []
                        (detect "mass" [ "last" ])
        , skip <|
            test "detects anagrams case-insensitively" <|
                \() ->
                    Expect.equal [ "Carthorse" ]
                        (detect "Orchestra" [ "cashregister", "Carthorse", "radishes" ])
        , skip <|
            test "detects anagrams using case-insensitive subject" <|
                \() ->
                    Expect.equal [ "carthorse" ]
                        (detect "Orchestra" [ "cashregister", "carthorse", "radishes" ])
        , skip <|
            test "detects anagrams using case-insensitve possible matches" <|
                \() ->
                    Expect.equal [ "Carthorse" ]
                        (detect "orchestra" [ "cashregister", "Carthorse", "radishes" ])
        , skip <|
            test "does not detect a word as its own anagram" <|
                \() ->
                    Expect.equal []
                        (detect "banana" [ "Banana" ])
        , skip <|
            test "does not detect a anagram if the original word is repeated" <|
                \() ->
                    Expect.equal []
                        (detect "go" [ "go Go GO" ])
        , skip <|
            test "anagrams must use all letters exactly once (go)" <|
                \() ->
                    Expect.equal []
                        (detect "tapper" [ "patter" ])
        , skip <|
            test "eliminates anagrams with the same checksum" <|
                \() ->
                    Expect.equal []
                        (detect "mass" [ "last" ])
        , skip <|
            test "detects unicode anagrams" <|
                \() ->
                    Expect.equal [ "ΒΓΑ", "γβα" ]
                        (detect "ΑΒΓ" [ "ΒΓΑ", "ΒΓΔ", "γβα" ])
        , skip <|
            test "eliminates misleading unicode anagrams" <|
                \() ->
                    Expect.equal []
                        (detect "ΑΒΓ" [ "ABΓ" ])
        , skip <|
            test "capital word is not own anagram" <|
                \() ->
                    Expect.equal []
                        (detect "BANANA" [ "Banana" ])
        , skip <|
            test "anagrams must use all letters exactly once (banana)" <|
                \() ->
                    Expect.equal []
                        (detect "patter" [ "tapper" ])
        ]
module Anagram exposing (detect)


detect : String -> List String -> List String
detect word candidates =
    let
        baseWord =
            String.toLower word

        letters =
            toSortedLetters baseWord
    in
    candidates
        |> List.filter (isAnagram baseWord letters)



-- PRIVATE


toSortedLetters : String -> List String
toSortedLetters word =
    word
        |> String.split ""
        |> List.sort


isAnagram : String -> List String -> String -> Bool
isAnagram word letters candidate =
    let
        candidateWord =
            String.toLower candidate
    in
    not (isSameWord word candidateWord) && hasSameLetters letters candidateWord


isSameWord : String -> String -> Bool
isSameWord word candidate =
    word == candidate


hasSameLetters : List String -> String -> Bool
hasSameLetters letters candidate =
    letters == toSortedLetters candidate

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