Parry language design

tags : [[programming languages]] [[programming language implementation]] [[my programming languages]] [[language design]]

Parry is a programming language I’d like to implement. Parry is inspired by Riposte.

Design

Parry programs are centered around making REST requests. The goal of Parry is to make REST requests scriptable. Parry should make it trivial to, say, do a GET request from one resource and then use that information in subsequent requests.

url_root = "api.example.com"

resource = get "${url_root}/foo"
another_resource = get "${url_root}/bar?id=${resource.id}"

let
    url = "${url_root}/baz"
    headers = {
        Content-Type: "application/json",
    }
    body = {
        parent_id: another_resource.id
    }
in
    post url headers body

Types

Parry is a loosely typed language and supports many basic types.

Primitives

Booleans

bool = true || false

Numbers

Parry supports integers and floating point numbers.

v = 1 + 3.22 - -1 * -3.45

Strings

str = "hello world"
strSingle = 'single quotes are okay too'

String interpolation can occur in any string.

strInterp = "${str} foo bar"

Lists

Lists can have mixed types and do not require commas.

[1 2 "foo" true]

Sets

Sets are a simplified kind of JSON. They are also immutable.

obj = {
    foo: 123,
    bar: 'bar',
    baz: false,
    quux: [1 2 3 4],
    quuz: {
        foo: 'foo'
    },
}

Set properties are accessed with dots.

foo = obj.foo
bar = obj?.bar # returns `null` if not present

To derive a new set, you can use the spread operator.

obj2 = {
    ...obj1,
    foo: 456 # overrides `foo`
}

Functions

All functions are first class, lambdas, and anonymous.

myFunc = (bar, baz) -> bar + baz;

Operators

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
<	Greater than
<=	Greater than or equal
>	Less than
>=	Less than or equal
.	Set access
?.	Optional set access
=	Assignment
>>	Write to file
<<	Read file to value

Control Flow

let … in

let
    a = 1
    b = 2
    c = 3
in
    a + b + c

Conditionals

Conditionals are expressions.

a = if isEven(4) then true else false

match

a = match b
    | "foo" -> 1
    | "bar" -> 2
    | else -> 3

Loops

File IO

Both reading and writing return null.

Reading

txt << "~/file.txt"

Writing

"foo bar" >> "~/out.txt"

REST requests

Making REST requests are at the center of Parry.

All REST requests are functions that either take a single string or a set. If only a string is specified, say

get "api.example.com/foo"

The request made will simply be a GET to that URL, with no further information.

However, you could also specify a set, as such:

get {
    url: "api.example.com/foo",
    headers: {
        Accept: "*/*"
    }
}

By passing a set you can specify header and body information.

get

post

Standard Library

Map

map([1 2 3], (v) -> "${v}") # => ["1" "2" "3"]

Reduce

reduce([1 2 3], (sum, v) -> sum + v, 0) # => 6

Assert