DATX02-DIT561

Daison Frontend

This project is the result of a Bachelor's thesis in Computer science and engineering (DATX02 / DIT561), given at Chalmers University of Technology and University of Gothenborg.

The purpose of the project is to study how the compiler GHC can be used as a library to build a front-end for Daison. The project focuses in particular on how GHC as a library can be used to build interactive Haskell environments.

Project structure

Setup.hs - Default setup for building executables.
src/ - Haskell sourcecode
- Main.hs - Start the program
- Frontend/ - Contains the Haskell sourcecode.
  - Base.hs - Session/State handling
  - Context.hs - Extensions/Flag handling
  - Eval.hs - Evaluate expressions sent through the CLI
  - Format.hs - Format output from Daison queries
  - GHCInterface.hs - No own implementations here, purely for imports.
  - Run.hs - Loop of the program and definitions of commands that can be run
  - Typecheck.hs - Typecheck user input to decide how to handle it.
tests/ - Contains automated tests for the program
- Tests.hs - Functional tests run with QuickCheck
- UnitTests.hs - Unit tests run with HUnit

Running the application

We used Cabal to automate dependency installations, building as well as testing the project. Run the following commands from the source folder:

Run:

cabal run daison-frontend

Test:

cabal test

Build executable

cabal build exe:daison-frontend

Get a simple binary in the folder dist/

cabal install exe:daison-frontend --install-method=copy --overwrite-policy=always --installdir=dist

Example usage

Start the program

~$ daison-frontend

Open a database

:open database.db

Load a local file with table and type definitions (people :: Table Person, Person :: Person { name :: String, age :: Int})

:load People.hs

Create a table which is defined in People.hs

tryCreateTable people

Read all entries in the people table

select [x | x <- from people everything]

Insert a new person into the table people

insert people $ return $ Person "Alice" 15

Update her age

let pkey = fst it
update people [(pkey, person{age=25}) | person <- from people (at pkey)]

Close the program

:quit

Available commands

Command	Description
`<statement>`	evaluate/run `<statement>`
:dbs	print the list of databases that are currently open
:?, :help	display this list of commands
:log path	display the log file's path
:log show	display the log file's contents
:log toggle	enable/disable logging
:log wipe	attempt to wipe the log file's contents
:type `<expr>`	show the type of `<expr>`
:q, :quit	quit the program
:! `<command>`	run the shell command `<command>`
:close `<name>`	close database with `<name>` if opened
:mode `[mode]`	set access mode to `[mode]` if provided; displays the current access mode otherwise
:open `<name>`	open database with `<name>` or set focus to `<name>` if already opened
:cd `<dir>`	set the current directory to `<dir>` (relative to current location)
:module `<module>`	import `<module>` if it exists and is in scope
:load `<filepath>`	load a haskell file from `<filepath>`
:set `<option>`	set GHC `<option>`

Authors

Name	GitHub-handle
Christoffer Kaltenbrunner	kaltenbrunner
Alexander Neldefors	PUGzera
Hugo Stegrell	steget
Philip Vedin	pvedin

kaltenbrunner/DATX02-DIT561