Intro

Jasper Van der Jeugt
Fugue
Declare config in a DSL
Server is set up and continuously reinforced / monitored

DSL in the Architecture

Conductor
Can update, kill, monitor server
DSL Inspired Haskell, Ocaml
- Compiler written in Haskell

Why we don't use YAML

There are shortcomings
Ansible - language isn't really composable
- Can create trouble / be difficult to manage
Scope and rules are not really clear
Configuration defaults??? location not really defined
Error messages unclear

Design Goals

Simple tasks should be simple
- Need very low overhead
Advanced things should be clean
Not general purpose language

Typed Language

Looks like yaml, but actually typed
Type inferencing or explicit typing
Structural type system for records
Scoped labels
- Practical with simple rules
- Improvement on scoped label disadvantages:
  - Extending record same as updating record

Records & Patterns

Update fields within fields
update through constructors
Records not enough - Abstraction needed
Functions
- Remove repitition
- included with syntactic sugar
  - Traditional () for wide understanding
- Various shorthands

Named Parameters

Not that easy in functional lang
Use 'records' to give names to arguments
- Keeps type inference and makes other interactions easier
Problems/fixes with record usage:
- None padding with coersions
- Optional lifting
Optional type gets special treatment, but the benefits are worth it