Ok yes, this is how we naturally speak. But when an English teaching magazine prints this stuff, then students think they can use it in their written work.
Written “gonna” and “wanna” should be used only in very informal texts and to give literary characters’ speech an authentic feel.
And in Spice Girls lyrics.
[/rant over]
I don’t know…seems OK if it’s a transcription of actual speech.
I get that. But we normally don’t write things like “We hafta go” when quoting someone, even though that’s what it sounds like. We write the correct “We have to go.” For an article on speech patterns and linguistics, sure. But for a news quote?
I wanna agree with you, but I hafta say I’m gonna go with that passage as it’s written. 
Lemme share this one too. Awesome. And a bit freaky.
Yeah, both of these show up in my university students’ submitted work a lot - they often have the wrong idea about when “wanna” is the correct register.
On the other hand, some native speakers do use it sometimes, so learning to recognize it has benefits. I’d be pretty happy to see a student use it correctly all things told 
And then it could be easily pointed out what contexts it is appropriate or inappropriate in.
On the prehistoric land mass known as GonnaWannaLand the dinosaurs taught English to our mammalian ancestors.
I’m curious - when do native speakers use it in writing? Transcription, maybe, although even then I’d probably “correct” it, unless I’m trying to capture a specific accent or pronunciation in dialogue.
For example, in forumosa I swear and I use “yeah” and “yup” and use fragments. Because it’s the internet. But I don’t think I’d ever type “wanna” or “gonna”. But maybe that’s just me. (“Buh mebbee das jus me”.)
I type “gonna” all the time, but maybe that’s just the Philistine in me.
I’m not sure that has a single answer, but I’m sure we all recognize them as existing written words (whatever your opinion on their correctness or desirability). I guess mostly transcription as you say, or texting. I think they were fairly common pre-texting-era though.
I remember in the 2008 elections, CNN put up a transcript of Sarah Palin’s speech about something, and they wrote ‘wanna’ and ‘gonna’ and left out dropped Gs; things they didn’t do for Biden, Obama, or McCain- they just wanted to characterize her as an ignorant hick. It was wrong and they should have been ashamed of themselves (but weren’t). Sorry, derailing, but it’s a long-standing peeve.
Just for fun I tried speaking to Google Translate in a normal voice, “Are you gonna let that slide?”.
Google Translate transcribed it as “Are you going to let that slide”?
“I’m gunna git yew!” was also correctly transcribed as “I’m going to get you”.
I guess they have a huge corpus with correct, formal transcriptions.
As a side note, I have to say Google Translate is an amazing boon to language learning. Sure, it ain’t no substitute for a real live partner – but being able to roughly check your pronunciation, and to listen to roughly correct pronunciation of any text – is quite remarkable when you think about it.
I’ve been struggling to undo this with my college students. Especially when they send me messages and write papers/essays. Part of the problem is that most of them don’t read and their English will never go beyond what is needed to pass some stupid test.
I share the sentiment that students 1) need to distinguish formal speech and writing from the colloquial spoken form, and 2) when appropriate (and it rarely is in the uni context) they need to know how to use informal language correctly (which they rarely do).
The “I’m gonna/wanna to …” form is particularly cringe worthy. I don’t speak in these reduced forms and avoid excessively connected speech in general, unless intentionally illustrating its use/misuse. It’s on par with going around saying “wayma?” in that “fake cute/pitiful” Taiwan utterance of “為什麼？”
I use that shit all the time. 
Or even the more relaxed “wuhmuh?”
Haha, hell yeah. I love it. The students get a kick out of my 裝可憐 Chinese when I’m in the mood. Doesn’t play so well with colleagues/officials/random strangers, haha!
I wouldn’t use it on officials, but colleagues and random strangers? Hellz yeah.
Depends on context. And mood. I like to play with language (perhaps not so much in the classroom, where I’d better elaborate on theories or provide etymology for word analysis).
Outside the classroom I let my proverbial hair down:
)But, not to many shenanigans in the classroom context
