Following is a example: h2 = Hash(String, Array(Time::Span)).new([] of Time::Span) # h2["foo"] = h2["foo"].dup unless h2.has_key?(key) h2["foo"] << 1.second pp h2 # => {} pp h2.keys # => [] pp h2["foo"] # => [00:00:01] When pp on h2, there is no key “foo” exists, but, when visit it use h2["f…

This has been explained in the document. API doc As an alternative, you can use h2["foo"] += [1.second]

I do a benchmark on all known working solution, @Blacksmoke16 solution is the best on runtime and memory usage ▶ code ╰──➤ $ cr run --release 1.cr meth1 7.31 (136.75ms) (±17.06%) 139MB/op 1.41× slower meth2 8.41 (118.96ms) (±11.45%) 170MB/op 1.23× slower meth3 10.32 ( 96.89ms) (± 9.33%…

Pp! on a hash with default value?

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Blacksmoke16 December 31, 2024, 2:24pm 3

Duplicate of How to append to an Array that is a default Value of a Hash?.

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Pp! on a hash with default value?

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