#+title: Parry language design
- tags :: [[file:20210307152738-programming_languages.org][programming languages]] [[file:20210411214221-programming_language_implementation.org][programming language implementation]] [[file:20210429105507-my_programming_languages.org][my programming languages]] [[file:20210429133404-language_design.org][language design]]

Parry is a programming language I'd like to implement. Parry is inspired by
[[https://docs.racket-lang.org/riposte/][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.
#+begin_example
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
#+end_example
* Types
Parry is a loosely typed language and supports many basic types.
** Primitives
*** Booleans
#+begin_example
bool = true || false
#+end_example
*** Numbers
Parry supports integers and floating point numbers.
#+begin_example
v = 1 + 3.22 - -1 * -3.45
#+end_example
*** Strings
#+begin_example
str = "hello world"
strSingle = 'single quotes are okay too'
#+end_example

String interpolation can occur in any string.

#+begin_example
strInterp = "${str} foo bar"
#+end_example
** Lists
Lists can have mixed types and do not require commas.

#+begin_example
[1 2 "foo" true]
#+end_example
** Sets
Sets are a simplified kind of JSON. They are also immutable.
#+begin_example
obj = {
    foo: 123,
    bar: 'bar',
    baz: false,
    quux: [1 2 3 4],
    quuz: {
        foo: 'foo'
    },
}
#+end_example

Set properties are accessed with dots.

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

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

#+begin_example
obj2 = {
    ...obj1,
    foo: 456 # overrides `foo`
}
#+end_example
** Functions
All functions are first class, lambdas, and anonymous.

#+begin_example
myFunc = (bar, baz) -> bar + baz;
#+end_example
* 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
#+begin_example
let
    a = 1
    b = 2
    c = 3
in
    a + b + c
#+end_example
** Conditionals
Conditionals are expressions.
#+begin_example
a = if isEven(4) then true else false
#+end_example
** match
#+begin_example
a = match b
    | "foo" -> 1
    | "bar" -> 2
    | else -> 3
#+end_example
** Loops
* File IO
Both reading and writing return =null=.
** Reading
#+begin_example
txt << "~/file.txt"
#+end_example
** Writing
#+begin_example
"foo bar" >> "~/out.txt"
#+end_example
* 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

#+begin_example
get "api.example.com/foo"
#+end_example

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

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

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

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

** =get=
** =post=

* Standard Library
** Map
#+begin_example
map([1 2 3], (v) -> "${v}") # => ["1" "2" "3"]
#+end_example
** Reduce
#+begin_example
reduce([1 2 3], (sum, v) -> sum + v, 0) # => 6
#+end_example
** Assert