I vote for I'm'a, myself, as telofy suggests, but I have also seen it spelled I'mma, which works for me also, mainly because it acknowledges the more familiar contraction with the apostrophe, but it's not optimal. "Imma" does have the drawback that rolig points out.
Bilby, the question is about where the expression "I'ma/Imma/I'm'a/I'm 'a/I'm a-" comes from, and how it should be spelled, when the "a" particle indicates the immediate future tense (in standard English we would say, "I'm going to let you finish"; Kanye said, "I'm'a let you finish.")
Yes, thanks a lot, rolig. And I’m delighted to know that there are other people bothered by such uncertainties/inconsistencies. After consulting that article (and the poll, but I’m not sure that can be called “consulting�?) I’m unsure whether that space is really as omission-worthy as is implied there, after all it’s usually a slow process—stepping on a hyphen intermediately—that leads up to that degree of coalescence. However the bigger the gap the more ambiguous seems the stress to me; one might be prone to assign a secondary stress to the “’a�?. So I’m not entirely convinced, but inclined to settle for I’m’a as a viable utilitarian compromise. For now.
This very question is currently being discussed over at Language Log, Telo. Personally, I don't like the spelling "Imma", which looks like it should rhyme with the word "dimmer" (British received pronunciation). I would vote for "I'm 'a" since it's pretty clear that the "a" is a contraction of "gonna" (I'm going to > I'm gonna > I'm 'na > I'm 'a). I'm not sure Kanye actually pronounces a double "m", but if he does this would have arisen through assimilation of the "n" in "gonna".
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