Overview

This article was also published on the site: Java Code Geeks.

Clojure is a passionate language that uses strong mathematical expressions for you to write a code, I think it’s cool. I am not a language expert, in fact in any language, I have a general profile, I decided to create a small banking application for study and testing purposes.

Before starting I will leave 3 book recommendations:

Tools

Dexter’s labs:

Development Environment

I’ve used clojure with Leiningen and use the Emacs editor that perfectly matches with Clojure. For more information check here:

Clojure Book

1. Project Design

The idea of the small bank is to create a Rest API using Clojure, where the user can do:

1.1 Start

I did tests on the FreeBSD / Mac OS and Ubuntu operating systems you can download the project:

git clone https://github.com/edersoncorbari/small-bank.git

Now you need to raise the HTTP server.

./launch-app

By default the server uses port 3000. On another terminal run the curl response test:

./launch-curl

You should get the following outputs in response:

-------------------------------------------------------------------------------------
*** Simple Rest API to Check/Balance Small-Bank ***

Please use the (curl-api-test) script for testing.
-------------------------------------------------------------------------------------
Add money account: 1 -> Crediting: 316.22776601683793319988
:> Successful transaction
Add money account: 2 -> Crediting: 447.21359549995793928183
:> Successful transaction
Add money account: 3 -> Crediting: 547.72255750516611345696
:> Successful transaction
Add money account: 4 -> Crediting: 632.45553203367586639977
:> Successful transaction
Add money account: 5 -> Crediting: 707.10678118654752440084
:> Successful transaction
Add money account: 6 -> Crediting: 774.59666924148337703585
:> Successful transaction
Add money account: 7 -> Crediting: 836.66002653407554797817
:> Successful transaction
Add money account: 8 -> Crediting: 894.42719099991587856366
:> Successful transaction
Add money account: 9 -> Crediting: 948.68329805051379959966
:> Successful transaction
Add money account: 10 -> Crediting: 1000.00000000000000000000
:> Successful transaction
Add money account: 11 -> Crediting: 1048.80884817015154699145
:> Successful transaction
Add money account: 12 -> Crediting: 1095.44511501033222691393
:> Successful transaction
Add money account: 13 -> Crediting: 1140.17542509913797913604
:> Successful transaction
Add money account: 14 -> Crediting: 1183.21595661992320851346
:> Successful transaction
Add money account: 15 -> Crediting: 1224.74487139158904909864
:> Successful transaction

-------------------------------------------------------------------------------------
Get balance account: 1
{"account":1,"date":"2018-11-04T18:27:18.915-03:00","balance":316.22776601683796}
Get balance account: 2
{"account":2,"date":"2018-11-04T18:27:18.929-03:00","balance":447.21359549995793}
Get balance account: 3
{"account":3,"date":"2018-11-04T18:27:18.939-03:00","balance":547.7225575051662}
Get balance account: 4
{"account":4,"date":"2018-11-04T18:27:18.949-03:00","balance":632.4555320336759}
Get balance account: 5
{"account":5,"date":"2018-11-04T18:27:18.961-03:00","balance":707.1067811865476}
Get balance account: 6
{"account":6,"date":"2018-11-04T18:27:18.972-03:00","balance":774.5966692414834}
Get balance account: 7
{"account":7,"date":"2018-11-04T18:27:18.982-03:00","balance":836.6600265340755}
Get balance account: 8
{"account":8,"date":"2018-11-04T18:27:18.993-03:00","balance":894.4271909999159}
Get balance account: 9
{"account":9,"date":"2018-11-04T18:27:19.004-03:00","balance":948.6832980505138}
Get balance account: 10
{"account":10,"date":"2018-11-04T18:27:19.017-03:00","balance":1000.0}
Get balance account: 11
{"account":11,"date":"2018-11-04T18:27:19.026-03:00","balance":1048.8088481701516}
Get balance account: 12
{"account":12,"date":"2018-11-04T18:27:19.041-03:00","balance":1095.4451150103323}
Get balance account: 13
{"account":13,"date":"2018-11-04T18:27:19.056-03:00","balance":1140.175425099138}
Get balance account: 14
{"account":14,"date":"2018-11-04T18:27:19.066-03:00","balance":1183.2159566199232}
Get balance account: 15
{"account":15,"date":"2018-11-04T18:27:19.083-03:00","balance":1224.744871391589}

-------------------------------------------------------------------------------------
Remove money account: 1 -> Debting: 31.62277660168379331998
:> Successful transaction
Remove money account: 2 -> Debting: 44.72135954999579392818
:> Successful transaction
Remove money account: 3 -> Debting: 54.77225575051661134569
:> Successful transaction
Remove money account: 4 -> Debting: 63.24555320336758663997
:> Successful transaction
Remove money account: 5 -> Debting: 70.71067811865475244008
:> Successful transaction
Remove money account: 6 -> Debting: 77.45966692414833770358
:> Successful transaction
Remove money account: 7 -> Debting: 83.66600265340755479781
:> Successful transaction
Remove money account: 8 -> Debting: 89.44271909999158785636
:> Successful transaction
Remove money account: 9 -> Debting: 94.86832980505137995996
:> Successful transaction
Remove money account: 10 -> Debting: 100.00000000000000000000
:> Successful transaction
Remove money account: 11 -> Debting: 104.88088481701515469914
:> Successful transaction
Remove money account: 12 -> Debting: 109.54451150103322269139
:> Successful transaction
Remove money account: 13 -> Debting: 114.01754250991379791360
:> Successful transaction
Remove money account: 14 -> Debting: 118.32159566199232085134
:> Successful transaction
Remove money account: 15 -> Debting: 122.47448713915890490986
:> Successful transaction

-------------------------------------------------------------------------------------
Get balance account: 1
{"account":1,"date":"2018-11-04T18:27:19.359-03:00","balance":284.604989415154167}
Get balance account: 2
{"account":2,"date":"2018-11-04T18:27:19.372-03:00","balance":402.492235949962134}
Get balance account: 3
{"account":3,"date":"2018-11-04T18:27:19.382-03:00","balance":492.950301754649586}
Get balance account: 4
{"account":4,"date":"2018-11-04T18:27:19.394-03:00","balance":569.209978830308315}
Get balance account: 5
{"account":5,"date":"2018-11-04T18:27:19.405-03:00","balance":636.39610306789284}
Get balance account: 6
{"account":6,"date":"2018-11-04T18:27:19.416-03:00","balance":697.13700231733506}
Get balance account: 7
{"account":7,"date":"2018-11-04T18:27:19.429-03:00","balance":752.99402388066794}
Get balance account: 8
{"account":8,"date":"2018-11-04T18:27:19.440-03:00","balance":804.98447189992431}
Get balance account: 9
{"account":9,"date":"2018-11-04T18:27:19.450-03:00","balance":853.81496824546243}
Get balance account: 10
{"account":10,"date":"2018-11-04T18:27:19.463-03:00","balance":900.0}
Get balance account: 11
{"account":11,"date":"2018-11-04T18:27:19.473-03:00","balance":943.92796335313644}
Get balance account: 12
{"account":12,"date":"2018-11-04T18:27:19.483-03:00","balance":985.90060350929907}
Get balance account: 13
{"account":13,"date":"2018-11-04T18:27:19.494-03:00","balance":1026.1578825892242}
Get balance account: 14
{"account":14,"date":"2018-11-04T18:27:19.503-03:00","balance":1064.89436095793088}
Get balance account: 15
{"account":15,"date":"2018-11-04T18:27:19.513-03:00","balance":1102.27038425243009}

The above test add new accounts, then checks the balance, and then takes money out of the accounts. You can see more details of the implementation by looking at the project’s README file.

Considerations

This is project is only used for studies using clojure, developed by layman in the subject and perhaps not one of the best implementations, techniques and use of the language.