Hello, World!

Written by: Hongwei Xi (the creator of ATS)

Intro

I suppose that you have already gained access to the commands tempacc, tempopt. If you have not, there are quite a few resources on-line that can guide you through the process of installing ATS (more precisely, ATS-Temptory) on your own machine.

Let us go through the few lines of code in Hello.dats quickly. One can form a line-comment in ATS by starting the line with two slashes (//). One can also form a block-comment in ATS by using the ML-style of commenting:

(*
...here-is-a-block-comment...
*)

The following lines are for staloading (that is, statically loading) some library code that the ATS compiler (ATS/Postiats) may need for the purpose of compilation:

#include "share/HATS/temptory_staload_bucs320.hats"

I will give some explanation elsewhere on using library functions in the construction of ATS programs. In order to compile a program into an executable, the special function named main need to be implemented. In the following code, main0 is a variant of main:

implement main0() = println! ("Hello", ", world!")

Note that the body of main0 is required to be of the type void. The function-like println! prints its arguments to the standard output and then prints a newline at the end. I use the name function-like to refer to something in ATS that is like a function but is not actually a function.

There is a Makefile provide for compiling the code. One can also use the following command-line for compilation:

mytempacc -o Hello_dats Hello.dats

which should generate an executable of the name Hello_dats. By executing Hello_dats, one sees the expected output:

>> ./Hello_dats
<< Hello, world!

Happy programming in ATS-Temptory!!!