cat.age:3
# {"age":3}
Defining "l" as in the example in the article. We need the "list" operator to enlist nested values so that the "," operator doesn't concatenate them into a flat list: l:1,(list 2,list cat),4
# (1,(2,{"age":3}),4)
Updating the "age" field in the nested dictionary. Lil's basic datatypes are immutable, so "l" is rebound to a new list containing a new dictionary, leaving any previous references undisturbed: l[1][1].age:9
# (1,(2,{"age":9}),4)
cat
# {"age":3}
There's no special "infix" promotion syntax, so that last example would be: l:l,5
# (1,(2,{"age":9}),4,5)
[0] http://beyondloom.com/tools/trylil.html> The more interesting example is reassigning the deeply nested l to make the cat inside older, without mutating the original cat
Isn't that mutating l, though? If you're concerned about mutating cat, shouldn't you be concerned about mutating l?
It's quite handy, though the syntax for it is rather clunky compared to the rest of the language in my opinion.