I often wonder when working on Spem what part of speech a word should be. Most concepts could be any. For example, "run" could be an adjective in its base form meaning "running", and we could convey "run" with "be running". Likewise, "green" could've been a verb meaning "to be green", and we could get the adjective with "I used the one that greens", instead of "I used the green one".

Those are both parameterless words - neither one takes an object. The case is a little different for things that have parameters. For example, consider the words "surround" and "around".

They mean the same thing, but one is a verb and the other is a preposition. "Surround" is an alias for "be around", and "around" is an alias for "surrounding". So prepositions are essentially adjectives with parameters. That's a neat insight.

But, there are some adjectives (or nouns) that take parameters. One example is "parent". In English, "parent" by itself is understood as "parent of someone, not specified who", and to specify who, we use "of". In Spem, this word is currently pel. pel's job is to convert an adjective to a preposition, opening its paramater slot which isn't accessible by default.

Familial relationship words are probably a bad example because they're used most often with the parameter (and hence I plan to make them prepositions when I add them). "Other" is a better example. "Other" is an adjective despite that the concept requires a parameter; "other than" is the preposition version. In this case, "than" is pel.

The three main descriptive parts of speech have the following tradeoff:

Therefore,

It's also interesting to note that in Japanese, relative clauses don't take a separator word and go before the noun they modify, meaning verbs don't pay a speed penalty when used subordinately. (And taking advantage of this, almost all Japanese "adjectives" are actually verbs.) I really did consider that for Spem but I decided against it on the grounds of intuition/clarity; the content of the relative clause should not come before the modified noun or any indication that it's a relative clause, because that's a recipe for confusion such as garden path sentences. But of course the question's still open. If you have thoughts, don't hesitate to post them because I'll absolutely change anything about Spem if I can be convinced it'd be better a different way, no matter how big an overhaul it'd require.

But, notably, that's what I do with adjectives. My de facto standard as of now is to put adjectives before nouns. My reasoning is that adjectives don't cause such confusion because they don't contain a secondary verb and are usually shorter. (The de facto standard with prepositions is to put them after, so they can't be mistaken for applying to more words than they're meant to.)

Open question: Should pel die?

I'm actually thinking about removing pel. It seems inelegant to me, since most often nouns or adjectives that accept a parameter should just be verbs or prepositions; yo is pretty much the only word justifying pel's existence as far as I can think of. And that doesn't seem like enough. kor/hɑr seem like borderline cases to me. Let me know your thoughts in the comments.