95 lines
2.3 KiB
EmacsLisp
95 lines
2.3 KiB
EmacsLisp
;;; iso.el --- Isomorphisms in Elisp -*- lexical-binding: t -*-
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;; Author: William Carroll <wpcarro@gmail.com>
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;;; Commentary:
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;; Providing basic isomorphisms to improve code quality.
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;;; Code:
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(require 'dotted)
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(require 'tuple)
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(require 'symbol)
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(require 'string)
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(require 'list)
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(require 'alist)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Library
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(cl-defstruct iso to from x)
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(defconst iso/whitelist
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'((dotted . tuple)
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(symbol . string))
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"Alist representing supported isomorphisms.")
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(defconst iso/vertices
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(list/concat (alist/keys iso/whitelist)
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(alist/values iso/whitelist))
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"List of all of the vertices in the iso graph.")
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(defun iso/classify (x)
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"Return type of X."
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(cond
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((string/instance? x) 'string)
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((symbol/instance? x) 'symbol)
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((dotted/instance? x) 'dotted)
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((tuple/instance? x) 'tuple)))
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(cl-defun iso/exists? (to from)
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"Return t if an isomorphism of TO to FROM exists."
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;; TODO: All of this can be improved modelling this with a graph.
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(cond
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;; to -> from
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((list/contains? to (alist/keys iso/whitelist))
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(list/contains? from (alist/values iso/whitelist)))
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;; from -> to
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((list/contains? from (alist/keys iso/whitelist))
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(list/contains? to (alist/values iso/whitelist)))
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;; doesn't exist
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(t nil)))
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(progn
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(prelude/assert
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(iso/exists? 'symbol 'string))
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(prelude/assert
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(iso/exists? 'dotted 'tuple))
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(prelude/refute
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(iso/exists? 'dotted 'symbol))
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(prelude/refute
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(iso/exists? 'symbol 'list)))
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;; TODO: Model this as a graph.
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(defconst iso/morphisms
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'((string .
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'(symbol #')
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))
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(list (:from 'string :to 'symbol :fn #'intern)
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(:from 'symbol :to 'string :fn #'symbol-name)
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)
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"")
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(defun iso/to (f x)
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"Apply F to X's to."
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(->> x
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iso-to))
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(->> (iso/new "william" :to 'symbol)
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(iso/as-to #'symbol-name)
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)
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(cl-defun iso/new (x &key to)
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"Create a new isomorphism of X mapping to TO."
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(let ((from (iso/classify x)))
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(prelude/assert (iso/exists? to from))
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(make-iso :from from
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:to to
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:x x)))
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(macros/comment
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(iso/new "william" :to 'symbol)
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(iso/new '(one . two) :to 'tuple))
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(provide 'iso)
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;;; iso.el ends here
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