Editing Lojban (section)

=== Repeating ===

Words <code>mi</code>, <code>do</code> correspond to English personal pronouns I (me), you. Lojban has other similar words, e.g. <code>ri</code>. Word <code>ri</code> fills in an argument (of the predicate) which repeats the previous argument.

{| border=5
| Somebody
| talks
| to somebody
| about something
| in some language
|-
| <math>x_1</math>
| predicate
| <math>x_2</math>
| <math>x_3</math>
| <math>x_4</math>
|}

A little vocabulary:
; <code>mi</code>
: I, me
; <code>do</code>
: you
; <code>la lojban.</code>
: Lojban
; <code>tavla</code>
: talk

Syntax:

{| border=5
|+ I talk to you about the Lojban language in Lojban
| <code>mi</code>
| rowspan=2 | <code>cu</code>
| <code>tavla</code>
| <code>do</code>
| <code>la lojban.</code>
| <code>la lojban.</code>
| rowspan=2 | <code>vau</code>
|-
| <math>x_1</math>
| predicate
| <math>x_2</math>
| <math>x_3</math>
| <math>x_4</math>
|}

<code>mi cu tavla do la lojban. la lojban. vau</code>

The word <code>ri</code> helps us avoiding repeating the argument of predicate in this case:

<code>mi cu tavla do la lojban. ri vau</code>

I think, it is a rather imperative solution (using some notion of state / memory), compared to the <math>\mathbf W</math> combinator of [[combinatory logic]], but in this case, it has the same effect. If Lojban used combinators, I should write (using the elementary duplicator <math>\mathbf W</math>):

<math>\mathbf W</math>(<code>mi cu tavla do</code>) <code>la lojban. vau</code>

It seems to me even better to modify only the predicate directly, not an arbitrary subexpression of the sentence -- if it is possible. Thus the deferred combinator <math>\mathbf W_{\left(2\right)}</math> helps us even more here:

<code>mi cu</code> (<math>\mathbf W_{\left(2\right)}</math> <code>tavla</code>) <code>do la lojban. vau</code>

<math>\mathbf W</math>-sequences could be used also for avoiding the many-many repeating zo'e words (of course, if Lojban used combinators):

I talk.

(Not specified, to whom, about what topic, in what language!)

<code>mi cu tavla zo'e zo'e zo'e vau</code>

What could help us in lambda calculus?
:<math>\lambda f x y . f x y y y</math>

<code>mi cu</code> (<math>\left(\lambda f x y . f x y y y\right)</math> <code>tavla</code>) <code>zo'e vau</code>

In [[combinatory logic]], <math>\mathbf W^2_{\;\left(1\right)}</math> makes that (let us note the little slant of the indices: powered combinator <math>\mathbf W^2</math> is deferred here, not deferred combinator <math>\mathbf W_{\left(1\right)}</math> is powered!):

<code>mi cu</code> (<math>\mathbf W^2_{\;\left(1\right)}</math> <code>tavla</code>) <code>zo'e vau</code>

Lojban does not use combinators this way, it uses also rather imperative solutions. Despite of that, Lojban makes me think of [[combinatory logic]] and [[Libraries and tools/Linguistics/Applicative universal grammar|applicative universal grammar]].