Ada: First Steps

Recently, I have come to make my first steps in Ada. I have been reading the book Ada 2022 by John Barnes but had to figure out some details setting up an editor and a compiler chain.

Here, I share some practical tips how to get started.

Alire

Alire is a package manager provided by AdaCore. It comes as a script. Place it in any folder accessible from the PATH, e.g., ~/bin.

Afterwards, I add the path ~/.alire/bin to the PATH. For this, extend the file ~/.profile to contain

# .profile

if [ -d "$HOME/.alire/bin" ] ; then
    PATH="$HOME/.alire/bin:$PATH"
fi

GNAT (GNU NYU Ada Translator) is an open-source implementation of an Ada compiler. Install GNAT using Alire:

alr install gnat gprbuild

Hello World

-- hello_world.adb

with Ada.Text_IO;

procedure Hello_World is
    use Ada.Text_IO;
begin
    Put_Line("Hello world.");
end Hello World;

GNU Make Workflow

What follows is a simple GNU Make-based workflow. Herein, GNAT’s manages all source dependencies. Accordingly, the $(MAIN) target does not name any dependencies.

In this example the dependency root is the procedure Hello_World stored in hello_world.adb.

# Makefile

AC      := gnat
ACFLAGS := -g -gnatw.e

MAIN    := hello_world

.PHONY: all
all:
       $(AC) make $(ACFLAGS) $(MAIN)

.PHONY: clean
clean:
       $(AC) clean $(MAIN)

With this Makefile in place, build the project like this:

make

GPRbuild Workflow

GPRbuild is a build system for Ada projects. It requires a project file describing the project.

Building an Application

-- src/hello_world.gpr

project Hello_World is
    for Main use ("hello_world.adb");
    for Source_Dirs use ("src");
    for Object_Dir use "build";

    package Compiler is
        for Default_Switches ("Ada") use ("-g", "-gnatw.e");
    end Compiler;
end Hello_World;

Building a Library

-- lib.gpr

project Lib is
    for Library_Name use "lib";
    for Library_Kind use "dynamic";
    for Source_Dirs use ("src");
    for Object_Dir use "build";

    package Compiler is
        for Default_Switches ("Ada") use ("-g", "-gnatw.e");
    end Compiler;
end Lib;

With this project file in place, build the project like this:

gprbuild

IDE Setup

This section describes how to set up various IDEs. I have found, however, that I was unable to set up GNATbench.

Emacs Setup

Enable MELPA, then install the following package:

ada-ts-mode

Sublime Text Setup

Enable Package Control, then install the following package:

Visual Studio Code Setup

Here, I describe how to setup Visual Studio Code. In the Settings, set the following:

Chat, Miscellaneous: check Disable AI Features.

Install the following extensions:

Ada & SPARK
Emacs Friendly Keymap

Open the project directory via File, Open Folder....

From the main menu select ..., Terminal, Configure Default Build Task.... Select ada: Build current project.

You can now build the project via ..., Terminal, Run Build Task....

You can run the project via Run, Run Without Debugging.

Debugging

Ensure, that the flag -g is enabled as an Ada compiler flag. Now, debug the executable the same way a C executable would.

gdb hello_world

Unit Testing with AUnit

See

AUnit Cookbook