Hindi is the best-studied language in South Asia. It would not be the worst thing if every linguist working on Hindi decided to take a break and pick any other language of the region to study. Nonetheless, Hindi does not set a relatively high bar for linguistic investigation when compared to other languages of the world; there is plenty that simply hasn't been described in any work by a linguist, let alone analysed or explained.
I've gone through several grammars of Hindi in my decade-long quest to recover something close to native-speaker status in my L1. (This is a not uncommon frustration among Indian-Americans.) My favourite is Kachru (2006), which covers many aspects of the language in a fairly accessible format. It was the first linguistic grammar I ever read and probably the only one I've ever gone through cover-to-cover. But surprisingly, there are many strange properties of Hindi morphosyntax that I have not seen described in any comprehensive grammar, and none of the papers I've read. This is an attempt to document some of these verb forms. Imperatives are also attested.
V[pfv] karnā
This construction is used to express a very habitual action. I have largely seen it in the past tense; it seems weird to use it with other tenses, and web searches informally appear to only attest the past tense.
pūr-e din mẽ ḍeṛʰ rupa-e k-ā ek vaṛā-pāv kʰā-y-ā kar-t-ā tʰ-ā
whole-M.OBL day LOC 1½ rupee-OBL GEN-M.SG one vada.pav eat-PFV-M.SG do-IPFV-M.SG be.PST-M.SG
“In the whole day, he used to eat a single 1½-rupee vada pav.” (Dai̯nik Bʰāskar)
hāy mar jā-ẽg-e / ham to luṭṭ jā-ẽge / ai̯s-ī bāt-ẽ kiy-ā nā kar-o
sigh die go-FUT.1PL-M.PL / 1PL TOP be.looted go-FUT.1PL / such-F.PL talk-PL do.PFV-M.SG NEG do-IMP.2PL
“Oh, I’ll die / I’ll be made worthless / Don’t keep saying such things!” (Āj jāne kī zidd nā karo, Farīdā Xānum)
What is weird is that the main verb takes the perfective while the light verb takes the imperfective, which makes no sense at all since that assigns conflicting aspectual values to the event! That violates one of the usual properties of serial verb constructions universally: shared aspectual features on all verbs in the SVC.
The usual way to express a habitual action in Hindi is the imperfective (see below).
vo roz jā-t-ā tʰ-ā
3SG every.day go-IPFV-M.SG be.PST-M.SG
“He used to go every day.”
The perfective, however, is ambiguously the habitual or just a single event, without extra information. In the sentence above, the temporal adjunct roz makes it clear that the event repeats. Compare this:
vo jā-t-ā h-ai̯
3SG go-PFV-M.SG be-3SG
“He goes (once/habitually).”
Presumably, with the need to talk about an unambiguous habitual event, this kind of construction developed to fill the gap.
V[ipfv] rahnā
The history of rahnā has been studied in the linguistic literature, as a transparent grammaticalisation of “to remain” into a continuous aspect marker. It's gaining in popularity in other languages due to the influence of Hindi–Urdu; see Slade (2013). What's interesting here is that it can be used with not only a bare stem, but also the imperfective-aspect main verb!
jī-te rah-o beṭ-e
live-IPFV stay-IMP.2PL child-VOC
“Bless you, child.” (said when one’s child touches one’s feet)
You may ask again, how can one serial verb construction take two different (and contradictory?) aspectual features? I say, the weird verb morphosyntax I've been discussing makes an absolute mess of the TAM system of Hindi. But note that this grammaticalisation is identical to that of stay V-ing in African-American Vernacular English.
V[cnv] rahnā
This is transparently a grammaticaled converbial construction, where what was previously literally two separate events (V-ing and then staying put) is now analysed as a strong will towards performing the event V.
āj kah-kar rah-ū̃g-ā
today say-CONV stay-FUT.1SG-M.SG
“Today I will say it no matter what.”
The grammaticalisation of converbs in Indo-Aryan languages is pretty interesting. Converbs are prototypically supposed to indicate a separate event from that of the main verb, but there are many instances in Hindi and other IA languages of a converb describing the same event as the main verb, which probably diachronically developed from a more literal reading. For example, paṛʰ-ke sunānā “to read then tell” > “to read out loud”.
References
- Yamuna Kachru. 2006. Hindi. Amsterdam/Philadelphia: John Benjamins Publishing Company.
- Benjamin Slade. 2013. The diachrony of light and auxiliary verbs in Indo-Aryan. Diachronica 30(4): 531–578.