ABC words: Difference between revisions

=={{header|JavaScript}}==

<lang javascript>(() => {

"use strict";

// -------------------- ABC WORDS --------------------

// isABC :: String -> Bool

const isABC = s =>

// True if the string contains each of 'a' 'b' 'c',

// and their first occurrences in the string are

// in that alphabetical order.

bind(

bind(

residue("a")("bc")(s)

)(

residue("b")("c")

)

)(

r => r.includes("c") || null

) !== null;

// residue :: Char -> String -> String -> Maybe String

const residue = c =>

// Any characters remaining in a given string

// after the first occurrence of c, or null

// if c is not found, or is preceded by any

// excluded characters.

excluded => {

const go = t =>

(0 < t.length) ? (() => {

const x = t[0];

return excluded.includes(x) ? (

null

) : c === x ? (

t.slice(1)

) : go(t.slice(1));

})() : null;

return go;

};

// ---------------------- TEST -----------------------

const main = () =>

lines(readFile("~/unixdict.txt"))

.filter(isABC)

.map((x, i) => `(${1 + i}, ${x})`)

.join("\n");

// --------------------- GENERIC ---------------------

// bind (>>=) :: Maybe a -> (a -> Maybe b) -> Maybe b

const bind = mb =>

// Null if mb is null, or the application of the

// (a -> Maybe b) function mf to the contents of mb.

mf => null === mb ? (

mb

) : mf(mb);

// lines :: String -> [String]

const lines = s =>

// A list of strings derived from a single string

// which is delimited by \n or by \r\n or \r.

Boolean(s.length) ? (

s.split(/\r\n|\n|\r/u)

) : [];

// readFile :: FilePath -> IO String

const readFile = fp => {

// The contents of a text file at the

// given file path.

const

e = $(),

ns = $.NSString

.stringWithContentsOfFileEncodingError(

$(fp).stringByStandardizingPath,

$.NSUTF8StringEncoding,

e

);

return ObjC.unwrap(

ns.isNil() ? (

e.localizedDescription

) : ns

);

};

// MAIN ---

return main();

})();</lang>

{{Out}}

<pre>(1, aback)

(2, abacus)

(3, abc)

(4, abdicate)

(5, abduct)

(6, abeyance)

(7, abject)

(8, abreact)

(9, abscess)

(10, abscissa)

(11, abscissae)

(12, absence)

(13, abstract)

(14, abstracter)

(15, abstractor)

(16, adiabatic)

(17, aerobacter)

(18, aerobic)

(19, albacore)

(20, alberich)

(21, albrecht)

(22, algebraic)

(23, alphabetic)

(24, ambiance)

(25, ambuscade)

(26, aminobenzoic)

(27, anaerobic)

(28, arabic)

(29, athabascan)

(30, auerbach)

(31, diabetic)

(32, diabolic)

(33, drawback)

(34, fabric)

(35, fabricate)

(36, flashback)

(37, halfback)

(38, iambic)

(39, lampblack)

(40, leatherback)

(41, metabolic)

(42, nabisco)

(43, paperback)

(44, parabolic)

(45, playback)

(46, prefabricate)

(47, quarterback)

(48, razorback)

(49, roadblock)

(50, sabbatical)

(51, snapback)

(52, strabismic)

(53, syllabic)

(54, tabernacle)

(55, tablecloth)</pre>