# Jester

A simple programming language, typed using algebraic subtyping.

## Usage

Jester syntax is Clojure data structures. Compiling Jester code consists of passing a data structure representing the program to `jester.compiler/compile-form` and calling the resulting function with a single argument.

```clojure
(require '[jester.compiler :refer [compile-form]])
(def f (compile-form '(string= "a" "b")))
(f nil) ;;=> false
```

Jester expressions can carry implicit dependencies on the argument structure. Any free names within a Jester script are looked up by keyword in the function argument:

```clojure
(def name-is-john (compile-form '(string= name "John")))
(name-is-john {:name "John"}) ;;=> true
(name-is-john {:name "Steve"}) ;;=> false
```

Keywords can be looked up in values with a dotted syntax reminiscent of many modern languages.

```clojure
(def person-name-is-john (compile-form '(string= person.name "John")))
(person-name-is-john {:person {:name "John"}}) ;;=> true
(person-name-is-john {:person {:name "Steve"}}) ;;=> false
```

If the input structure doesn't match the required rule structure, an exception will be thrown.

```clojure
(person-name-is-john {:name "John"}) ;; => throws exception
```

## Quirks

String comparisons are case insensitive. This is usually what humans want out of language.