Inspired by some concepts in programming recently I’ve come up with the idea that は marks an environment and が marks a variable inside an environment.
Environment and variable:
An example of environment:
猫は
┌───────────────────┐
│ E: cat │
│ │
│ │
│ │
│ │
│ │
│ │
└───────────────────┘
This is an environment with the name 猫.
Many things can exist inside this environemnt:
┌───────────────────┐
│ E: cat │
│ ----------------- │
│ behavior nyan │
│ │
│ cute liquid │
│ │
│ mouse ... │
└───────────────────┘
An example of variable:
猫が
v: cat
This is just a variable with the name 猫.
私は猫が
┌───────────────────┐
│ E: I │
│ │
│ │
│ │
│ │
│ │
│ v: cat │
└───────────────────┘
This is the depiction of an variable with the name 猫 inside an environemnt with the name 私.
Some sentences
Sentence 1: 猫が好きだ
This sentence can have any of following meanings according to context
a) Generally speaking, cats are liked [猫が好きだ]
b) As for me, cats are liked (-> I like cats) [私は猫が好きだ]
c) As for ? (someone or something according to context), cats are liked [◯は猫が好きだ]
a)
v: cat───────► liked
b)
┌───────────────────┐
│ E: I │
│ │
│ │
│ │
│ │
│ │
│ v: cat──┼────► liked
└───────────────────┘
c)
┌───────────────────┐
│ E: ? │
│ │
│ │
│ │
│ │
│ │
│ v: cat──┼────► liked
└───────────────────┘
Sentence 2: 猫は好きだ
This sentence can have any of following meanings according to context.
a) Generally speaking, as for cats, everything about cats is liked. [猫は好きだ]
b) Generally speaking, as for cats, ? about cats is liked. [猫は◯が好きだ]
c) As for me, as for cats, everything about cats is liked. (-> I like cats) [私は猫は好きだ]
d) As for me, as for cats, ? about cats is liked. [私は猫は◯が好きだ]
a)
┌───────────────────┐
│ E: cat │
│ │
│ │
│ │
│ │
│ │
│ ├───────► liked
└───────────────────┘
b)
┌───────────────────┐
│ E: cat │
│ │
│ │
│ │
│ │
│ │
│ v: ? ──┼───────► liked
└───────────────────┘
c)
┌───────────────────────────────┐
│ E: I │
│ │
│ │
│ ┌───────────────────┐ │
│ │ E: cat │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ ├──┼────► liked
│ └───────────────────┘ │
└───────────────────────────────┘
d)
┌───────────────────────────────┐
│ E: I │
│ │
│ │
│ ┌───────────────────┐ │
│ │ E: cat │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ │ v: ? ───┼──┼────► liked
│ └───────────────────┘ │
└───────────────────────────────┘
Sentence 3: 猫好きだ
I think here 猫 can be either an environment or an variable.
Environment & variable vs topic & subject: I think this environment model explains things betther than the use of the terms “topic” and “subject”, at least for me.
I took inspirations from following sources:
a) Lesson 3: WA-particle secrets schools don’t ever teach. How WA can make or break your Japanese (by Cure Dolly)
https://www.youtube.com/watch?v=U9_T4eObNXg&list=PLg9uYxuZf8x_A-vcqqyOFZu06WlhnypWj&index=3
b) Environment model in “Structure and Interpretation of Computer Programs”
I am certainly no expert in Japanese it’s been more than 20 years since I lived there.
But one of my ways of understanding は and が is like in them to the articles “the” and “a”. The former is talking about something that has not been mentioned before, or is unique. The latter is referring to an object that the listener knows.
To use your programming analogy, maybe it’s like differentiating between an object and a class.