Rupert  Beatty

Rupert Beatty


Web IDE for The Picat Language Based on Blazor and Monaco


Web IDE for the Picat programming language based on .net Blazor and Monaco. It provides common moder code editor features like syntax highlighting, code completion with documentation preview (CTRL+Space), indentation helpers, occurences highlighting, search, etc. and compilation/execution of code via an associated compiler wrapper service.

This editor aims to aid in learning Picat syntax and editing Picat programs.

Technical details

The editor is based on 2 components:

  1. The front-end page: this where the core editing experience resides. It's built using Blazor and Monaco, and runs using client-side WASM.
  2. The Web Api compiler service. a thin HTTP server wrapping the Picat compiler command line program. It's task is to forward code to the compiler to parse, compile and run programs and to return the output. Please note that you can still use the front-end standalone for code editing, however you will need the service if you want to parse, compile and run programs.

Running the IDE

You have several options for how to host the IDE:

  • You can use the Live demo as is, and just start the compiler web service on your machine to get the full IDE experience
  • Build the sources using VisualStudio and .net Core 5, and start from VS
  • Run the attached Windows release binaries

Features playground

The editor comes with a tutorial example that showcases the major features:

% Welcome to the Picat editor based on Blazor and Monaco!
% This editor aims to aid in learning Picat syntax and editing Picat programs.
% Below you will get a step by step introduction to the available features.
% The editor relies on a compiler service to do the actual compilation and code execution,
% and to enable some of the features. Nevertheless, it is still possible to get a basic
% editing experience without the service running.
main => foo.

% Syntax highlighting and basic operations:
% The typical editing operations known from modern code editors are available, this includes:
% copy-paste, undo, auto-intendation on Enter, selection highlighting, Alt+Shift+Click block editing, Ctrl+F search, etc.
% You can try some of them by editing the below code:
foo() => bar,
         bar, bar.

% Code completion:
% You can bring up the code completion options by pressing Ctrl+Space.
% Documentation of most built-in functions is included,
% and documentation for your own functions is taken from the comment preceding the declaration.
% If the documentation is not displayed, you can open by clicking 'Read More' on the very right of a completion entry.
% Try bringing up the completion for 'fo' to see it in action:
foo2 => fo.

% Built-ins hover documentation:
% When it comes to built-in functions in existing code you can view their documentation either by:
% - Ctrl+Space to bring their completion entry
% - Mouse hover
% You can try this below:
bar => println(hello).

% Go to declaration:
% For your own functions, you can easily navigate to it's declaration by Ctrl+Click or the context menu.
% Try going to 'foo' through the below code:
car => foo.

% Syntax error highlighting (requires compiler service):
% Your code will get compiled in the background as you type, and also when you decide to run it.
% Any syntax errors discovered will be market in red, and a hover tooltip to the code describing the error.
% The compiler output will be shown in the output panel, and you can double click 
% the '*** SYNTAX ERROR ***' message to quickly navigate to the target code fragment.
% Please try it out on the below code, and use it to help you fix it.
dar =>
    true :-) .

% Code execution (requires compiler service):
% You can run your program by supplying a goal, and clicking the Run button.
% The output will be presented in the output panel.
% Please note that the editor is not meant as a full-featured runner - you should always use you local Picat compiler for serious runs.
% The editor runner limitations include: interactive user input is not supported, max execution time limited to 10s.
% Give it a go by running the 'main' goal.

% Unit tests (requires compiler service):
% The editor provides a convention for defining unit tests:
% they are argument-less predicates whose name starts with 'test_', and they can either succeed, fail, or throw.
% Unit tests are a great way to gain confidence in the individual pieces of your program, and ensure that any refactorings
% or additions of new features do not break the existing logic.
% Tests are executed in a randomized order to prevent sequence-dependence, and their total execution time is limited to 15s.
% Below you can find some example tests, press 'Run All' in the Tests panel to run them:
test_foo => foo.
test_fail => fail.
test_dar() => dar.
test_dar2() => this_do_not_exist(A, B, c, d).
test_throw => X is 1/0.

% Custom links:
% If you want to share a code example link with someone, you can define a custom link to this editor
% by inserting your code as UrlEncoded value of the 'code' parameter like in the below example:
% https://localhost:5001?code=main+%3D%3E+bar.%0D%0Abar+%3D%3E+println(hello).

% Reporting errors:
% Please report any errors to the githu repository at:
% If possible, please include the contents of the JS console log after you have triggered the error (F12, or Developers tools in most browsers)


  • Currently only tested hosting on Windows. Though it's built on .net core, so should be possible to build for Linux/Mac with minimal or no code changes. If you want to contribute a non-Windows build or a Windows Docker image for the server, please send me a PR or a link to your builds.
  • Currently the Web API compiler service comes bundled with the Windows compiler - using on Linux/Mac would require the respective compiler version to be included. As a sidenote, the service implementation is very simple it's just a HTTP server that forwards request parameters to the compiler and returns the compiler outputs - it would be definitely possible to rewrite it in another language in an evening or two. See ValuesController.cs for reference.
  • The Web API compiler service contains no safety mechanisms, and thus will allow any code to be compiled and executed. This means it obviously should not be exposed on untrusted networks. Please only use on localhost or on trusted networks.

Live demo

A live demo of the code editor is available on the below link. It runs completely client-side and will not upload your code to the internet. Please note that this demo does not include the Web API Compiler component, so some features like syntax error highlighting, compilation, code execution and test runners will not be available. However, you can easily turn the demo into a complete IDE experience if you simply start the Web API Compiler service component on your own machine.

Author: Andrzejolszak
Source Code: 

#blazor #webassembly

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Buddha Community

Web IDE for The Picat Language Based on Blazor and Monaco
Jamal  Lemke

Jamal Lemke


Blazor for ASP.NET Web Forms Developers PDF

Blazor is a new web framework that changes what is possible when building web apps with .NET. It is also a client-side web UI framework based on C## instead of JavaScript. When paired with .NET running on the server, Blazor enables full-stack web development with .NET.

It also builds on the foundations of .NET Core to provide a modern and high-performance web development experience. Additionally, Blazor is a natural solution for ASP.NET Web Forms developers looking to take advantage of client-side development and the open-source, cross-platform future of .NET.

This e-book pdf covers the following ASP.NET Web Forms features and practices:-

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Asp.Net Web API Introduction

What is an API?

API stands for Application Programming Interface. API is some kind of interface which has a set of functions that allow programmers to access specific features or data of an application, operating system or other services using HTTP protocol.

When to choose ASP.NET Web API?

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API Features

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Blazor : Calling REST API ASP NET Core Blazor | WEB API

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Call DELETE API ASP NET Core Blazor | Blazor CRUD using API Part-4

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Call GET API ASP NET Core Blazor | Blazor CRUD using API Part-2

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