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group_map_reduce
Sequence.group_map_reduce
(K
type
:
property.orderable, B type
, key_f Unary K Sequence.T, f Unary B Sequence.T, reduce_f Binary B B B) =>
container.Map K B[Contains abstract features]
¶Type Parameters
type of the keys
0.094dev (2025-06-18 15:08:51 GIT hash 89cffc23ae669b0898a5564fefbf793fcb8e5ca7 built by fridi@fzen)
reduce elements within a group by first applying f and then using reduce_f to reduce
example: count occurrences of letters, numbers and other characters
values array codepoint := ["A", "1", "b", "?", "X", "4"]
classify (c codepoint) String => c.is_ascii_letter ? "letter" : c.is_ascii_digit ? "digit" : "other"
values.group_map_reduce String i32 classify (_->1) (+)
=> {(digit => 2), (letter => 3), (other => 1)}