Having just once again suffered through the dimly remembered pain of learning about Jekyll, Liquid, and hash arrays, I am recording it here to save myself the next time I go for a few years between dealing with it. Official documentation does not say this (enough?), I guess because they think, "They can't, so let's not bother talking about it." This leaves the experienced programmer new to Liquid going "I should be able to do this, why can't I just assign myHash = { one: 1, two: 2 } or ["one" => "1", "two" => "2"] or some combination of braces and quotes or other punctuation? Do I just have the syntax wrong???"

You can't. For some reason "they" don't want you to. So, define your hash array in the page _layout front matter, site _config.yml, or site _data/ if what you really want is to put it in the front matter of an _include (because there's no front matter for includes).

1. Hash arrays cannot be created within Jekyll+Liquid
   • vector arrays can
   • hash arrays can be created in front matter or .yml files