c1e381eecc
TL;DR: - prefer WPCARRO env-var to BRIEFCASE - remove repository URLs from Emacs libraries - prefer tvl-depot-path where possible - reduce the scope of constants.el - prune (some not all) stale CI configuration Change-Id: I21e9130402502ec6fa2fc4b46753c890069be62d Reviewed-on: https://cl.tvl.fyi/c/depot/+/4545 Tested-by: BuildkiteCI Reviewed-by: wpcarro <wpcarro@gmail.com>
108 lines
2.4 KiB
EmacsLisp
108 lines
2.4 KiB
EmacsLisp
;;; sequence.el --- Working with the "sequence" types -*- lexical-binding: t -*-
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;; Author: William Carroll <wpcarro@gmail.com>
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;; Version: 0.0.1
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;; Package-Requires: ((emacs "25.1"))
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;;; Commentary:
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;; Elisp supports a typeclass none as "sequence" which covers the following
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;; types:
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;; - list: '(1 2 3 4 5)
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;; - vector: ["John" 27 :blue]
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;; - string: "To be or not to be..."
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;; TODO: Document the difference between a "reduce" and a "fold". I.e. - reduce
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;; has an initial value whereas fold uses the first element in the sequence as
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;; the initial value.
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;;
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;; Note: This should be an approximation of Elixir's Enum protocol albeit
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;; without streams.
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;;
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;; Elisp has done a lot of this work already and these are mostly wrapper
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;; functions.
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;; See the following list for reference:
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;; - sequencep
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;; - elt
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;; - copy-sequence
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;; - reverse
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;; - nreverse
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;; - sort
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;; - seq-elt
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;; - seq-length
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;; - seqp
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;; - seq-drop
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;; - seq-take
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;; - seq-take-while
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;; - seq-drop-while
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;; - seq-do
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;; - seq-map
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;; - seq-mapn
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;; - seq-filter
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;; - seq-remove
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;; - seq-reduce
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;; - seq-some
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;; - seq-find
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;; - seq-every-p
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;; - seq-empty-p
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;; - seq-count
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;; - seq-sort
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;; - seq-contains
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;; - seq-position
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;; - seq-uniq
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;; - seq-subseq
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;; - seq-concatenate
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;; - seq-mapcat
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;; - seq-partition
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;; - seq-intersection
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;; - seq-difference
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;; - seq-group-by
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;; - seq-into
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;; - seq-min
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;; - seq-max
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;; - seq-doseq
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;; - seq-let
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;;; Code:
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;; Perhaps we can provide default implementations for `filter' and `map' derived
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;; from the `reduce' implementation.
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;; (defprotocol sequence
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;; :functions (reduce))
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;; (definstance sequence list
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;; :reduce #'list-reduce
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;; :filter #'list-filter
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;; :map #'list-map)
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;; (definstance sequence vector
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;; :reduce #'vector/reduce)
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;; (definstance sequence string
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;; :reduce #'string)
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(defun sequence-classify (xs)
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"Return the type of `XS'."
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(cond
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((listp xs) 'list)
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((vectorp xs) 'vector)
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((stringp xs) 'string)))
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(defun sequence-reduce (acc f xs)
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"Reduce of `XS' calling `F' on x and `ACC'."
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(seq-reduce
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(lambda (acc x)
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(funcall f x acc))
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xs
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acc))
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;; Elixir also turned everything into a list for efficiecy reasons.
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(defun sequence-filter (p xs)
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"Filter `XS' with predicate, `P'.
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Returns a list regardless of the type of `XS'."
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(seq-filter p xs))
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(defun sequence-map (f xs)
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"Maps `XS' calling `F' on each element.
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Returns a list regardless of the type of `XS'."
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(seq-map f xs))
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(provide 'sequence)
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;;; sequence.el ends here
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