The Haskell in-memory interactive database - HimiDB
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- Realised at MuniHac 2018
Idea
Joshua Backfield’s book, Becoming Functional: Steps for Transforming Into a Functional Programmer, introduces a very simple database engine written in Scala. This project is to convert this system into Haskell, and build a CLI frontend for it in a purer way than the Scala system uses.
Building and executing:
stack build
stack test
stack exec himiDB
Built With
- Haskellstack - The Haskell Tool Stack
- Hspec - A Testing Framework For Haskell
- Megaparsec - A Haskell parsing library, used for the CLI
- Haskeline - A Haskell command line interface
Demo
HimiDB v0.1
The Haskell In-Memory Interactive Database System
Created for the MuniHac 2018
type `help` for instructions
himiDB > create users (id int, name string) a table to describe my subscribers
himiDB > insert users (1, "me") (2, "you") (3, "him")
himiDB > insert users ("them", 4)
Error: Wrong type for column id
himiDB > describe
users (id int, name string) a table to describe my subscribers
himiDB > describe users
users: a table to describe my subscribers
id | name
int | string
----+-------
3 | "him"
2 | "you"
1 | "me"
himiDB > select users * where name == "me" || id > 2
3 | "him"
1 | "me"
himiDB CLI
Usage:
- create:
Create a table
> create myTable (a int, b int, c int)
> create tableName (col1 int, col2 string) description goes here
- drop:
Delete a table and its contents
> drop tableName
- describe:
Show all tables, or the data of one table
> describe
> describe tableName
- insert:
Insert a row into a table
> insert tableName (1, "me")
> insert tableName (1, "me") (2, "you")
- select:
Select data from a table
> select tableName *
> select tableName col1
> select tableName (col1, col2)
> select tableName * where col1 > 4 || col2 == "me"
- delete:
Delete data from a table
> delete tableName
> delete tableName where col1 > 4 || col2 == "me"
- help:
Show the help guide, with examples
- exit:
Exit and clear the database
> ^D