# Introduction
Minimacy is a combination of:
-	a high-level programming language
-	an instant compiler which compiles the high-level language into a bytecode
-	a virtual machine made of a virtual processor and a set of little independent instructions, written in C language
-	some of these instructions communicate with the underlying machine:
o	an OS based machine: Windows, Unix/Linux, MacOS, iOS, Android
o	or a bare-metal machine, such as a RaspberryPi
[<img class='mediumCenter' src='rsc/structure.png'/>](html)

As a developer, you may:
-	use the Minimacy programming language to implement your program
-	read the source code of the Virtual Processor and the instructions to fully understand how things are working
-	implement your own instructions in C when speed is critical or when you need to address a new hardware device
-	read the source code of the instant compiler for your own fun!

# Hello world
Let’s start with the "hello world" program.
Create a new file "hello.mcy", and enter the following line:
	fun main() = echoLn "Hello world!";;
What we can see there:
{
fun	we are declaring a function (because functions are fun;-)
main()	the name of the function
=	the result of the function follows the sign “equals”
echoLn	this system function takes one argument, displays it and appends a newline
"Hello world!"	the argument for the function echoLn
;;	this marks the end of the function declaration
}
Now you can start your program:
-	on windows: double-click on hello.mcy
-	on unix: [minimacy]/bin/minimacy hello.mcy
-	on macos: [minimacy]/bin/minimacyMac hello.mcy
>> Minimacy - Sylvain Huet - 2020-24 - 1.3.0/Windows
>> ----
>> 64 bits
>> Minimacy directory       : ~/minimacy/
>> Rom directory            : ~/minimacy/rom/
>> BIOS compiled in 5 ms
>> current time: Thu, 22 Feb 2024 18:32:39 UTC
>> compiling 'hello'
>>>>>>>>>> package: hello
>> fun main : fun -> Str
>> compiled in 0 ms
>
>Hello world!
>> end of line
{
\> 64 bits	This is the 64 bits version of Minimacy
\> Minimacy directory: ~/minimacy	The system directory. It is the directory containing the hello.mcy file
\> Rom directory: ~/minimacy/rom/	The rom directory. It contains the BIOS source files
\> BIOS compiled in 5 ms	The BIOS is written in Minimacy and is compiled first.
\> current time: Thu, 22 Feb 2024 18:32:39 UTC	On some baremetal targets, it is convenient to check the clock.
\> compiling 'hello'	Start the compilation of hello.mcy
\>>>>>>>>> package: hello	This starts the dump of the compiled hello package
\> fun main : fun -> Str	The inferred type of the "main" function
\> compiled in 0 ms	Always fast! but this one was simple
Hello world!	The evaluation of the "main" function calls the [[echoLn]] function which displays this message on the console
\> end of line	This is the last system message before Minimacy terminates on its own
}
What we learn from this example:
-	Minimacy is a virtual machine which runs the Minimacy language
-	Minimacy source files have ".mcy" extension
-	When Minimacy starts with a ".mcy" file argument, it compiles the source file and calls the function “main”
-	The function “main” has no argument
-	It stops automatically when there is nothing more to compute and nothing to wait for
-	the machine did not create any intermediary file, such as a binary or bytecode file
We wrote the function “main” in a single line but this was not mandatory. Minimacy does not take care of the spaces, tabulation or newlines. We could as well write it like this:
	fun main() =
		echoLn "Hello world!"
	;;

# Top-Level
Locate the file “topLevel.mcy” in the Minimacy directory, and launch it.
You get a Top-level interface with a prompt:
>Minimacy Top-level
>Ready
>]
It looks like a shell, but it is more than that. A dedicated empty package has been created for you and you can type either declarations as in a *.mcy file, and expressions.
The Top-level automatically adds “;;” at the end of each line.
>] 123+456
>-> Int: 579 (0x243)
The purpose of this Top-level is not to write full programs. It's just an easy way of testing system functions, and therefore very useful for discovering the Minimacy language.