Syphon

A functional, minimalist MVU based language for creating Desktop GUI apps powered by Electron and React. Heavily influenced by Haskell and Elm, with some new quirks mixed in.

Features

• Zero boilerplate 🚫

👾 Just plug 'n' play! No main function, the core logic of all programs comes from the definitions of init, update and view. Ideal for smaller projects. Example of a complete program:

alias State = Int

type Event = Inc | Dec

init :: State
init = 0

update :: State -> Event -> State
update s e = match e with
	Inc -> s + 1
	Dec -> s - 1

--Multiline list syntax sugar
view :: State -> Widget
view s = Column []<<
	Button (Text "+") Inc
	Text (toString s)
	Button (Text "-") Dec

Minimalist syntax and zero boilerplate means programs are generally very small and easy to reason about. Here is a simple calculator program, the logic should be clear to follow:

alias Operator = Int -> Int -> Int

type State = 
	{
	display :: String,
	operator :: Operator,
	operand1 :: Int
	}

type Event = Clear | Eq | OpPress Operator | Digit Int

--Use plus as a "dummy" opterator
init :: State
init = State "" (+) 0

update :: State -> Event -> State
update s e = match e with
	Clear -> init
	Eq -> State (calc s) (+) 0
	OpPress op -> State "" op $ parseInt s.display
	Digit i -> {s | display = append s.display (toString i)}
	where
		calc st = toString (st.operator st.operand1 (parseInt st.display))

view :: State -> Widget
view s = Column []<<
	--Optional structures allow tweaking properties of GUI widgets
	Container #{dim = (275,35), bgColor = Grey} $ Text s.display
	Row $ (map mkDigitButton [7..9]) ++ [Button (Text "X") (OpPress (*))]
	Row $ (map mkDigitButton [4..6]) ++ [Button (Text "/") (OpPress (/))]
	Row $ (map mkDigitButton [1..3]) ++ [Button (Text "-") (OpPress (-))]
	Row [mkDigitButton 0, Button (Text "AC") Clear, Button (Text "=") Eq, 
		Button (Text "+") (OpPress (+))]
	where
		mkDigitButton i = Button (Text $ toString i) (Digit i)

• Type Inference

  • Type system based on Hindley-Milner Algorithm W

• Helpful static analysis 🔎

• Cross platform 💻

  • CLI transpiler written in Haskell
  • Produces React based Electron apps

• Functional purity 😇

  • Explicit state management improves referential transparency and reduces the likelihood of illegal states
  • Side effects are only permitted from the system primitive definitions initEffects and effect
  • Ideal environment for beginners to learn functional programming applied to GUIs

• Quirky syntax features 🍭

• Performance 🚀

  • Widgets automatically detect if they need to be re-rendered based on the part of the state they display and checking it for changes
  • Harness the power of the React Virtual DOM algorithm

• A labour of love 💜

  • My final year project at The University of Southampton. If you are interested, have a read of my dissertation PDF
  • Currently searching for a software engineering role in the UK and open to offers of employment :)

Usage

• Clone or download (insert link) the repo:
• cd into the syphon directory
• Run ./make and the makefile will call ghc to produce the syphon binary
• Run ./syphon and the interactive CLI tool will start

Etymology

• The MVU architectural pattern is based on a unidirectional flow of data. From Wikipedia:

  A siphon (from Ancient Greek: σίφων, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes

Future goals

• An alternative implementation targetting a different platform such as creating Flutter smartphone apps
  • The syntax is designed to be fairly general on purpose with this future goal in mind!
• Lazy evaluation language primitive