In the sentance below, what is the grammar behind 唱えにゃならん?
これ小僧や、お前は、いずれはわしの代りにお寺でお経を唱えにゃならんのだぞ。
(I thought it was verb stem+にはならない with sound changes but I coudn't find such gramatical structure)
「にゃ」
is a colloquial pronunciation of both:
「ねば」 and 「には」
which means you must decide which one it is from the context.
In the phrase:
「唱{とな}えにゃならん」
「にゃ」 is short for 「ねば」. (Grammatically, you cannot say 「唱えには」 in the first place.)
So, the dictionary form of 「唱えにゃならん」 is 「唱えねばならない」, which means the same as 「唱えなければならない」= "must chant the sutra" .
"Listen, boy, you are going to have to chant the sutra instead of me at the temple one day."