Re: Why are Ada compilers difficult to write ?

[Lucretia <laguest9000@googlemail.com>]

On Tuesday, 19 June 2018 22:33:38 UTC+1, Vincent  wrote:
> Dear Ada programers,
> 
> I have often heard that Ada compilers where expensive because they are very difficult to write, compared to Pascal or C ones. So my question is : what in the Ada language poses problem to a compiler ? What are the challenges ? Where can I find documentation about that ?

Here are the issues I see:

1) Getting the grammar from the AARM correct, because it's highly ambiguous, doesn't include the pragmas (still!!!!) in the correct places and that it includes semantic info, especially for ID's.

2) There are many many many rules that have to be observed *and* documented for each implementation.

3) Overload resolution, as Jacob mentioned, it apparently a bitch.

4) It's a big language, including abstracted threaded via tasks, protected objects, so it's not as simple as just writing a Pascal subset.

Pascal as originally designed is tiny and can be implemented within a few days to a week. TBH I think I could knock up a Pascal scanner and parser in an afternoon, that's half of it done, stick it onto LLVM and it yer done.

C is a massive bag of shit and would take ages to write a *decent* compiler for, it has soooooooooooooooooooooooo many edge cases because it's such a mess. Even though, all it is, is a simple list of declarations (variable, constant, functions "prototypes"), function "bodies" and "types," but it's everything else that's the problem with C.