Golang is one of my favourite languages and I want to use it for a personal NLP/ML project. Is golang's ecosystem good and rich enough for this?
Is there an alternative package for nltk in golang?
No. Not yet
There is no single package in Golang, which acts as versatile as nltk for NLP. However, there are several packages which aim to do it.
Here is a compiled list of such packages: https://github.com/gopherds/resources/blob/master/tooling/README.md#nlp
You can have a look into this repository, it was recently announced in hacker news. I personally don't have experience using it, but the benchmarks look interesting:
prose is a natural language processing library (English only, at the moment) in pure Go. It supports tokenization, segmentation, part-of-speech tagging, and named-entity extraction.