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I want to write an elisp function, when a country name is given, it returns the short code for the country.

I've been reading about hash tables, but still not sure how to hashify my data set and make the function work:

Afghanistan,AF
Albania,AL
Algeria,DZ
American Samoa,AS
Andorra,AD
Angola,AO
Anguilla,AI
Antarctica,AQ
Antigua and Barbuda,AG
Argentina,AR
Armenia,AM
Aruba,AW
Australia,AU
Austria,AT
Azerbaijan,AZ
Bahamas,BS
Bahrain,BH
Bangladesh,BD
Barbados,BB
Belarus,BY
Belgium,BE
Belize,BZ
Benin,BJ
Bermuda,BM
Bhutan,BT
"Bolivia, Plurinational State of",BO
"Bonaire, Sint Eustatius and Saba",BQ
Bosnia and Herzegovina,BA
Botswana,BW
Bouvet Island,BV
Brazil,BR
British Indian Ocean Territory,IO
Brunei Darussalam,BN
Bulgaria,BG
Burkina Faso,BF
Burundi,BI
Cambodia,KH
Cameroon,CM
Canada,CA
Cape Verde,CV
Cayman Islands,KY
Central African Republic,CF
Chad,TD
Chile,CL
China,CN
Christmas Island,CX
Cocos (Keeling) Islands,CC
Colombia,CO
Comoros,KM
Congo,CG
"Congo, the Democratic Republic of the",CD
Cook Islands,CK
Costa Rica,CR
Côte d'Ivoire,CI
Croatia,HR
Cuba,CU
Curaçao,CW
Cyprus,CY
Czech Republic,CZ
Denmark,DK
Djibouti,DJ
Dominica,DM
Dominican Republic,DO
Ecuador,EC
Egypt,EG
El Salvador,SV
Equatorial Guinea,GQ
Eritrea,ER
Estonia,EE
Ethiopia,ET
Falkland Islands (Malvinas),FK
Faroe Islands,FO
Fiji,FJ
Finland,FI
France,FR
French Guiana,GF
French Polynesia,PF
French Southern Territories,TF
Gabon,GA
Gambia,GM
Georgia,GE
Germany,DE
Ghana,GH
Gibraltar,GI
Greece,GR
Greenland,GL
Grenada,GD
Guadeloupe,GP
Guam,GU
Guatemala,GT
Guernsey,GG
Guinea,GN
Guinea-Bissau,GW
Guyana,GY
Haiti,HT
Heard Island and McDonald Islands,HM
Holy See (Vatican City State),VA
Honduras,HN
Hong Kong,HK
Hungary,HU
Iceland,IS
India,IN
Indonesia,ID
"Iran, Islamic Republic of",IR
Iraq,IQ
Ireland,IE
Isle of Man,IM
Israel,IL
Italy,IT
Jamaica,JM
Japan,JP
Jersey,JE
Jordan,JO
Kazakhstan,KZ
Kenya,KE
Kiribati,KI
"Korea, Democratic People's Republic of",KP
"Korea, Republic of",KR
Kuwait,KW
Kyrgyzstan,KG
Lao People's Democratic Republic,LA
Latvia,LV
Lebanon,LB
Lesotho,LS
Liberia,LR
Libya,LY
Liechtenstein,LI
Lithuania,LT
Luxembourg,LU
Macao,MO
"Macedonia, the Former Yugoslav Republic of",MK
Madagascar,MG
Malawi,MW
Malaysia,MY
Maldives,MV
Mali,ML
Malta,MT
Marshall Islands,MH
Martinique,MQ
Mauritania,MR
Mauritius,MU
Mayotte,YT
Mexico,MX
"Micronesia, Federated States of",FM
"Moldova, Republic of",MD
Monaco,MC
Mongolia,MN
Montenegro,ME
Montserrat,MS
Morocco,MA
Mozambique,MZ
Myanmar,MM
Namibia,NA
Nauru,NR
Nepal,NP
Netherlands,NL
New Caledonia,NC
New Zealand,NZ
Nicaragua,NI
Niger,NE
Nigeria,NG
Niue,NU
Norfolk Island,NF
Northern Mariana Islands,MP
Norway,NO
Oman,OM
Pakistan,PK
Palau,PW
"Palestine, State of",PS
Panama,PA
Papua New Guinea,PG
Paraguay,PY
Peru,PE
Philippines,PH
Pitcairn,PN
Poland,PL
Portugal,PT
Puerto Rico,PR
Qatar,QA
Réunion,RE
Romania,RO
Russian Federation,RU
Rwanda,RW
Saint Barthélemy,BL
"Saint Helena, Ascension and Tristan da Cunha",SH
Saint Kitts and Nevis,KN
Saint Lucia,LC
Saint Martin (French part),MF
Saint Pierre and Miquelon,PM
Saint Vincent and the Grenadines,VC
Samoa,WS
San Marino,SM
Sao Tome and Principe,ST
Saudi Arabia,SA
Senegal,SN
Serbia,RS
Seychelles,SC
Sierra Leone,SL
Singapore,SG
Sint Maarten (Dutch part),SX
Slovakia,SK
Slovenia,SI
Solomon Islands,SB
Somalia,SO
South Africa,ZA
South Georgia and the South Sandwich Islands,GS
South Sudan,SS
Spain,ES
Sri Lanka,LK
Sudan,SD
Suriname,SR
Svalbard and Jan Mayen,SJ
Swaziland,SZ
Sweden,SE
Switzerland,CH
Syrian Arab Republic,SY
"Taiwan, Province of China",TW
Tajikistan,TJ
"Tanzania, United Republic of",TZ
Thailand,TH
Timor-Leste,TL
Togo,TG
Tokelau,TK
Tonga,TO
Trinidad and Tobago,TT
Tunisia,TN
Turkey,TR
Turkmenistan,TM
Turks and Caicos Islands,TC
Tuvalu,TV
Uganda,UG
Ukraine,UA
United Arab Emirates,AE
United Kingdom,GB
United States,US
United States Minor Outlying Islands,UM
Uruguay,UY
Uzbekistan,UZ
Vanuatu,VU
"Venezuela, Bolivarian Republic of",VE
Viet Nam,VN
"Virgin Islands, British",VG
"Virgin Islands, U.S.",VI
Wallis and Futuna,WF
Western Sahara,EH
Yemen,YE
Zambia,ZM
Zimbabwe,ZW
  • FWIW, there are several such lists in Emacs itself, so while adding one more won't hurt... – wasamasa Jul 5 '18 at 6:22
  • There are a few ways to implement a "lookup table" in Lisp. A hash table is only one way. See Hash Tables in the Elisp manual for some differences between hash tables and alists. – Drew Jul 5 '18 at 15:40
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It is a good idea to get to know the tools that your chosen language provides; for instance, Emacs Lisp provides the following built in functions: make-hash-table,gethash.

make-hash-table is a function that creates hash tables.

gethash returns the key's value. If the key doesn't exist it returns nil. So you do not need to formulate an abstraction. All you need is this.

(gethash hash-of-countries "Mexico")

But you could also formulate a function:

;; string hash -> key's value
;; purpose: returns the key's value given a key and a hash table.
;; given: (get-key-value "Mexico" hash-countries)
;; expect: MX
(defun get-key-value (str hsh)
  (gethash str hsh))

;; create a hash table
(setq hash-of-countries (make-hash-table :test 'equal))
(puthash "Mexico" "MX" hash-of-countries)
(puthash "United States" "USA" hash-of-countries)

https://www.gnu.org/software/emacs/manual/html_node/elisp/Hash-Tables.html#Hash-Tables

http://ergoemacs.org/emacs/elisp_hash_table.html

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