REST-STCK

Arbitrary Computation as a Service (ACaaS)

What is this?

Imagine a wonderful world where turing-complete computation could be preformed through elegant REST APIs. No longer just a fantasie, REST-STCK introduces REST-based computing to the masses.

Based on the award-winning, enterprise-grade programming language STCK, frontend developers can now leverage the power of Arbitrary Computation as a Service (ACaaS).

Try it out at stck.azurewebsites.net/stck

So how do I use this thing?

REST-STCK let's you preform STCK-computation through a REST API, using HAL - Hypertext Application Language to support HATEOAS.

Come again?

First, read the STCK readme, and make sure you understand stack-based programs and basic STCK syntax.

All done? Then let's continue.

You first visit /stck to start a computation. This will respond with a JSON-object containing your new STCK-computation and a collection of links. The links contain all the possible tokens you can add to your STCK expression. You can for instance follow the link to /stck/contexts/FFBECBFBA01644216AD5841A990338D3/tokens/zero to add zero to the current expression. Note how the expression part of the JSON-response now contains a zero. Add another zeroto the expression by visiting /stck/contexts/F40BB63810269123C1853105AD84F92B/tokens/zero, and note that you now have two zeroes in your expression.

Now we want to send the expression to the STCK-interpreter. This is done using /stck/contexts/EEF0655ABDFE9DFD73207563DD704CBA/tokens/eval. Note that now the expression part of the response is empty, and that the stack part contains [0, 0].

To recap, you follow the links to add STCK-operators (tokens) to your expression, and then evaluate your expression by following the eval-link.

Where did all the numbers go?

In order to be able to return a finite number of links to new computation states, the number of supported numbers are reduced to one number: zero. In order to construct different numbers you can use zero, along with the subroutine onemore. To get the number 3, you would for instance use zero onemore onemore onemore. In addition negative numbers can be constructed using two numbers and the sub subroutine.

What about conditionals, subroutine declaration, math operators and other stuff?

Since a lot of characters used in vanilla STCK needs to be URL-encoded, they are replaced with words in REST-STCK. For instance is <a boolean> ? <this will happen if true> : <this will happen if false> ; replaced with <a boolean> if <this will happen if true> else <this will happen if false> end, and # <expression> is replaced with defn <expression>.

Operators are mapped according to the following rules:

add = +
sub = -
mult = *
gt = >
lt = <
idiv = i
if = ?
else = :
drop = .
end = ;
mod = %
defn = #
bwap = swap
meep = dup
jump = over
mop = rot
howlong = len
eq = =
opposite = not
2meep = 2dup
div = /

Let's say I want to play with this on my own computer

Requirements

You'll need .Net Core to compile and run the project.

Installation

First, clone the project:

$> git clone https://github.com/teodoran/rest-stck.git

Then run the following commands to restore all nuget packages, build, and run the rest-stck server.

$> cd ./RestStck
$> dotnet restore
$> dotnet run

Now you should be able to navigate to localhost:5000/stck and try it out.

Project structure

The core STCK-interpreter is located under /CoreStck. This is a F# project based on the vanilla STCK-interpreter. Under /RestStck, you'll find the api-server. This is a C# project based on ASP.NET Core

TODO

There is a bug where execution contexts does not get an unique hash. It's probably because ToSting() is not the best way to get all information about the context object as input for the hash function...