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by butterisgood 1021 days ago
I want to like Ada, but the lack of support for Mac OS on anything Apple Silicon related is a huge reason to skip it and do something else (for me).

One thing I still haven't wrapped my head around is how "dynamic" memory allocation and cleanup works in Ada. It doesn't seem as important to mention that early in any documentation anywhere. And, maybe it's the C/C++ programmer in me, but that strikes me as a bit odd. Or, perhaps I just can't see past the tip of my nose and it's there.

I kind of need to know how dynamic memory works in any programming language before I plan to invest deeply in learning it. And it needs to work on my hardware.
2 comments
docandrew 1021 days ago
There’s a GNAT release for M1 now. The FSF Ada compiler is based on GCC so it has worked for RISC-V and other ARM CPUs for a little while now as well.

Ada’s dynamic memory principles are definitely unique. For heap allocation its based around memory pools, at least in GNAT. For the most part it’s RTTI but you can do manual new/free style too (though discouraged).

Ada uses a secondary stack as well for variable-length function returns, so in practice you don’t need to do heap allocation very much.

There are also equivalents of some STL containers like vector that can handle heap allocations for you safely.

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butterisgood 1021 days ago
Thanks for this... I'll take a look at how to get started on Mac OS with GNAT.

I went down a bit of a rabbit hole recently looking to see if there was a LLVM way to do this. It looked like it was being worked, but I'm not sure it's the best way to get started with Mac OS and Ada on Apple Silicon.

I'll check out homebrew and macports too... again, just in case!

Thanks again!

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MarcusE1W 1021 days ago
Not sure how well it works (I don’t have a Mac), but there is this repository that describes how to compile the whole gcc/gnat ada system in MacOS.

https://github.com/simonjwright/building-gcc-macos-arm-eabi

Bonus point is that you get the compiler for ARM bare metal

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docandrew 1021 days ago
Happy to help! I can also recommend alire (alire.ada.dev), the open source package manager for Ada. It can manage your toolchains for you and makes it very easy to get started and create new projects. It works well on M1s.
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OneWingedShark 1021 days ago
Memory management in Ada is such that you need pointers (and the heap) far, far less than in other languages: the language allows the return of values to objects of unconstrained subtypes to provide the constraints; example:

    Text : Constant String := Read_Chapter( Book );
Additionally, nesting DECLARE blocks and subprograms allows a fairly fine-tuned memory-usage/cleanup using the stack. The above example could, for example, be part of an outer DECLARE block, which has an inner DECLARE, perhaps with "Paragraphs : Constant String_Vector := Get_Paragraphs( Text );" in its declarative region and "For Paragraph of Paragraphs loop" in its body... as soon as the block is exited, the stack is popped, reclaiming the used memory. This, in turn, means that the need for heap allocation is greatly reduced.

Here's an excellent presentation on Ada's memory management: https://archive.fosdem.org/2016/schedule/event/ada_memory/

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