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Homoiconism

We coin the term "homoiconism" to refer to the procedures, analyses and related topics where non-homoiconic program code is transformed into homoiconic form, as this subject has not been investigated extensively elsewhere. We believe we have invented a novel, generalized procedure for transforming programs written in ANY known programming language into a Forth like Reverse Polish Notation syntax, known as the Inverse Shunting Yard Algorithm (ISYA), thus making homoiconism accessible to a much wider audience than previously possible.

https://en.wikipedia.org/wiki/Homoiconicity

While Wikipedia and the few literature briefly explored some issues concerning homoiconicity, we believe they can be addressed systematically using ISYA.

:: eval() vs. others??

ANY

:: quote minimum text concerning topic to be discussed (whatever concerned homoiconicity) to that readers can follow and look up.

We shall illustrate our work with some code examples first, before delving into further theoretical discussions.

Although the term homoiconic refers to the property of a programming language where code and data are represented using the same form (same="homo", form="icon"), the crux of the matter is the ability of a program to analyze and process the code of another program (including itself) written in the same programming language, although this motivation might not have been highlighted in existing literature.

Figures 1 and 2 show portions of code from SensorHelper.java from:

https://github.com/udexon/ReactiveSensors/blob/RxJava2.x/app/src/main/java/com/github/pwittchen/reactivesensors/app/SensorHelper.java

Phos is a stack machine shell (smashlet) that employs Forth like Reverse Polish Notation, as shown in line 43 and 45 of figure 2.

https://github.com/udexon/ReactiveSensors/blob/RxJava2.x/app/src/main/java/com/udexon/smashlet/Phos.java

Figure 1

Figure 2 

Phos.F(": now_sec now: colon: explode:   2 ia: ;");

Phos.F("rae: t tk:  3 bzk:  " +
       "t_exists_retrieve_t t tr: now_sec dup: t t:  fsub:");

Phos.F() takes a space delimited string, pushes non-function tokens on to the stack, and execute functions in the host programming language (in this case, Java) mapped by fuction words (tokens). The previous sentence basically summarizes the operations of a stack machine shell (smashlet). Due to its simplicity, it can be implemented in all known programming languages. We have successfully implemented Phos Smashlet in PHP, JavaScript and Java.

In line 45, the Phos statement is:

rae: t tk:  3 bzk:  
            t_exists_retrieve_t t tr: 
            now_sec dup: t t:  fsub:

Words with a colon suffix are function words that maps to functions in the host programming language. For example, rae: maps to S.removeAllElements() in line 1894, as shown in figure 3:

Figure 3

Word Definition
rae: S.removeAllElements()
t tk: if key t exists
k bzk: branch forward by k tokens if zero
t tr: read from key t
now_sec alias as defined in line 43
dup: duplicate top of stack
x v t: store x in variable v
fsub: float substract

The complete definitions for Phos function words are given in Phos.java.

Just like Forth, the result of an operation is pushed back on to the stack.

In summary, the pseudo code for line 45 is:

remove all elements on stack 
    ( this is necessary as createSubscription() is called every time a sensor value 
    is updated. )
    
check if key t (time) exists in tree T
    if not, branch forward by 3 tokens
    if t exists, read t and store the result on stack
    
get current time, store it in T['t']

substract previous value of T['t'] from current time

store the result on stack, to be read by line 49