Yes, I know about the 'random conlang questions' thread. I didn't know about it for my previous two posts. And this one, I think may require a more in-depth discussion.
Its an idea I had. A flaw in configurational languages is that it can be hard to determine the part of speech of everything. The rules for determining what roles everything plays in the sentence are insanely complicated, and even then ambiguity issues still arise.
I thought of a way to solve this: mark everything for part of speech. If say the language had adjectives come after nouns, then the noun would always mark the beginning of the noun phrase. So if it was somehow marked as a noun (such as in Esperanto), then parsing would be easy.
Of course, I don't know of any natural languages that mark part of speech like Esperanto does.But many languages do mark part of speech on at least some things, they just don't use specialize affixes like Esperanto does. You're not likely to find an affix that just indicates something as a verb. Rather, a language may rely on tense endings. If only verbs can take tense endings, then a word having a tense ending would automatically mark it as a verb. If nouns have cases (such as in Latin), then a word having a case ending would automatically imply a noun. Yeah, there's Tok Pisin which has an adjective suffix, though its often omitted in everyday speech. Regardless, part of speech affixes are rare, since you can just double up with endings that words are required to have anyway. I mean, why have a suffix for 'verb' when the tense marker would mark it anyway since only verbs can have one? And yes, there are languages where other parts of speech can have tense. Japanese allows adjectives to have tense, though their endings are different, and not all adjectives can even take tense marking. Also, only verbs can take honorific endings, adjectives can not, even when they act as a predicate (if they want such a sentence to be honorific, they just tack 'desu' onto the end, its also common to do that in other situations where there's no actual honorific ending to use).
I'm not trying to create an auxlang here (though I tend to design my conlangs like they are anyway, partially because that's how I got into conlanging, and besides, I think it saves work to keep things simple). I just thought it was an interesting idea. Yeah, if you want nouns to be marked as nouns then you can just use articles or case endings. But this seems kind of a compromise. Nouns are explicitly marked as nouns, but you don't have to deal with case endings or articles. Though admittedly you could also just have your nouns have a marked singular. A plural ending automatically implies a noun (in most languages anyway, Korean verbs can take a plural ending, to mark a distributive aspect). This means that having a noun ending too would be redudant. So if the language had grammatical number, then there wouldn't likely be a noun suffix (asides maybe for word derivination) but instead just singular and plural markers.