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How Dasher Works: The Library Concept

Imagine a Library Containing All Possible Books

Imagine a library containing all possible books, ordered alphabetically on a single shelf. Books in which the first letter is “a” are at the left hand side. Books in which the first letter is “z” are at the right.

In picture (i) below, the shelf is shown vertically with “left” (a) at the top and “right” (z) at the bottom. The first book in the “a” section reads “aaaaaaaaaaaa…”; somewhere to its right are books that start “all good things must come to an end…”; a tiny bit further to the right are books that start “all good things must come to an enema…”.

Dasher zooming interface animation (version 3)

The original "How does Dasher work?" page (DasherSummary2.html) used this animation on the right side.

Finding Your Book

When someone writes a piece of text, their choice of the text string can be viewed as a choice of a book from this library of all books - the book that contains exactly the chosen text.

How do they choose that book? Let’s imagine they want to write “all good things…”

First, they walk into the “a” section of the library. There, they are confronted by books starting “aa”, “ab”, “ac… az” [Picture (ii)].

(ii) Dasher showing letter regions while writing 'hello'

Looking more closely at a specific region

(iii) Higher-resolution Dasher screenshot showing probable next letters

Zooming further into the most likely continuations

Looking more closely at the "al" section, they can find books starting "ala", "alb"... "alz" [Picture (iii)].

By looking ever more closely at the shelf, the writer can find the book containing the text he wishes to write. Thus writing can be described as zooming in on an alphabetical library, steering as you go.

The Key Concept

This is exactly how Dasher works, except for one crucial point...