Lesson 03 · Building from a word list

Building from a word list

A real dictionary holds tens of thousands of words, loaded in one go from a word list. Today you add bulk loading and a size count so a whole vocabulary can arrive at once.

The goal

Load many words from a list in one call and report how many distinct words the dictionary holds.

Start here - the target

TO DO

Scenario: Loading a word list and counting it

Givenan empty dictionary

WhenAddAll(["cat", "dog", "Cat", "bird"]) is called

ThenSize() is 3 (the duplicate "Cat" folds into "cat")

AndContains("cat"), Contains("dog"), and Contains("bird") are all true

Background

Nobody types a vocabulary in by hand. A spell checker is seeded from a word list - a file with one word per line, from a few hundred to a few hundred thousand entries - so the dictionary needs a way to swallow a whole slice of words at once. AddAll is just Add in a loop, but making it a first-class call is what lets the rest of the project say “load a dictionary” in one line.

Size earns its place as the first thing you can observe about a loaded dictionary, and it quietly proves normalization works: adding cat and Cat leaves one word, not two, because both fold to the same key in the set. That de-duplication is free - it is the set doing its job - and it is the first hint that the same normalization will keep the whole checker consistent.

Make it work

func (d *Dictionary) AddAll(words []string) {
  // reuse Add for each - normalization and de-duplication
  // both fall out of the set you already have
}
func (d *Dictionary) Size() int {
  // number of distinct normalized words
}

CheckpointDONE

The dictionary loads a whole word list at once and reports its size. Commit and stop here.