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A guided intro to the Free Pascal language

getlazarus.org

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Re: A guided intro to the Free Pascal language

#71

Post by speed_spread »

cardanome wrote: post #61
speed_spread wrote: post #54

Earlier quoted context omitted.

It's not magic in how it works, it's just magic in it's syntax. It's a variable you don't have to declare. It's ripe for abuse / mistakes and would be one of the things I'd have lints for and watch closely in PRs.

Nim has the same result variable[1] and I absolutely love it. It helps avoid the classic "oh, I forgot to return it" bug. Also makes the code more succinct and saves you from having to type an extra line for explicit return. I kind of get why you would be wary of it, as it is a special variable but compared to other messed up stuff like for example Rust treating a line without semicolon as implicit return, it is a re…

Ha, I'm quite used to Rust's last-expression-is-the-value and I also get why some would think it's weird but I find it actually works quite well in practice. Each language has its gymnastics and special moves, I guess. Back to Pascal, I'm not opposed to Result usage per se and I understand the appeal since it's what I grew on. My concerns are more about code maintenance in long-ish functions - I don't have a particular example of mis-usage, but I'd be wary of late reassignments overriding a previously set value. Separating exit points from return value assignment could let code become hard to follow and create situations where it's easy to misread the actual outcome.

Re: A guided intro to the Free Pascal language

#72

Post by jksmith »

Peter5 wrote: post #51

Note for people who don't know much about FreePascal. It is a full-featured and very fast compiler. The resulting program is a rival for the best output of C/CPP compilers. It can be used in the style of simpler languages like Go and is almost as safe as Rust in a much faster manner. It has a great but old-looking IDE, Lazarus. It has been under active development for decades and is used for proper projects like: htt…

Yeah, but it's not hip, and it's too wordy with BEGIN/END, and the data structures are too restrictive, and the compiler nags you, and the like. And you can write an 8M line codebase in it, touched in all kinds of foul ways, and it still works. That's the biggest codebase I've ever worked on at least.

Take that as a small (subjective) clue. Anything that is great about Rust or Nim or could also have extended Pascal or M2 for the same result, and much sooner. Especially goes for M2, because the grammar was so small, thus avoiding the old PL1 traps from an overloaded parser.

FPC needs smart macros, needs to backport M2 interfaces, and the solid green thread spec* backported from M2, but it really is in the ballpark. You want gc? Well, fair enough, but you can write a pretty good mark/release* facsimile with RTTI. Or how about Eiffel simulated contracts with open arrays?

And Lazarus, good grief what a 30 year old premiere open source project. No point in even talking about how awesome it is.

Co-Pascal has been doing co-routines for 45 years.

In turbo pascal, you could create mini-heaps that could be dumped most anytime. They weren't smart, but still a cool feature.

Re: A guided intro to the Free Pascal language

#73

Post by twic »

slt2021 wrote: post #65
andai wrote: post #52

Earlier quoted context omitted.

You mention that Pascal is almost as safe as Rust. This comes as a great surprise to me, because I was under the impression that Pascal and C are very similar. (Though I hear the strings, at least, know their own size!)

I learned programming at school in Pascal and didn't have troubles with memory safety. FreePascal/Delphi has good standard library to work with strings and dynamic arrays and objects, and as long as you follow very simple convention with TObject.Create() and TObject.Free; you won't have memory safety problems. I didn't really have a need to work with pointers and do pointer math in Pascal, because language itself pro…

> as long as you follow very simple convention with TObject.Create() and TObject.Free; you won't have memory safety problems

Is this the same as how in C, as long as you follow very simple convention with malloc() and free() you won't have memory safety problems?

Re: A guided intro to the Free Pascal language

#74

Post by squarefoot »

A peculiar aspect of Lazarus (Free Pascal's Delphi-like IDE) is that it either cross-compiles for other architectures or can run itself on them, therefore generating native GUI software that runs immediately on the target platform. That is, you can develop ARM executables on a Raspberry PI using Lazarus running on the Pi itself. I would also suggest to take a look at FPCUpDeluxe, an installer that does all the tedious job of dealing with dependencies for installing FPC, Lazarus and a great number of modules and components.

https://wiki.freepascal.org/Lazarus_on_Raspberry_Pi

https://wiki.lazarus.freepascal.org/fpcupdeluxe

A personal dream: having something like Lazarus that works with other languages too; that would likely become a game changer for desktop apps development.

Re: A guided intro to the Free Pascal language

#75

Post by open-source-ux »

speed_spread wrote: post #36

I used to be a hard Delphi/Pascal guy and still think it is much better than C for it's strong typing and overall "squareness". But I'd have a hard time going back to it nowadays. The 'var' section, magic "Result" variable and begin/end pairs are just from another age. Programming languages have advanced _a lot_ since Pascal was created. It's core principles remain valid (safety by default, readability, flexibility).…

"The 'var' section, magic "Result" variable and begin/end pairs are just from another age...Programming languages have advanced _a lot_ since Pascal was created."

I understand why some programmers dislike Pascal's syntax, but C and C++ are also old and still popular (including for new projects). Syntax and semantics are closely entwined but C and C++ syntax still influence "modern" languages.

Re: A guided intro to the Free Pascal language

#76

Post by Akira1364 »

Don't download the bundled Free Pascal and Lazarus distributions from this site, they're very outdated. Just get the normal releases from the actual Free Pascal and Lazarus sites which are linked at the top of the page. Lazarus comes with Free Pascal bundled by default anyways, so you don't need to grab the compiler separately if using Lazarus.

Re: A guided intro to the Free Pascal language

#77

Post by suprjami »

andai wrote: post #52
Peter5 wrote: post #51

Note for people who don't know much about FreePascal. It is a full-featured and very fast compiler. The resulting program is a rival for the best output of C/CPP compilers. It can be used in the style of simpler languages like Go and is almost as safe as Rust in a much faster manner. It has a great but old-looking IDE, Lazarus. It has been under active development for decades and is used for proper projects like: htt…

You mention that Pascal is almost as safe as Rust. This comes as a great surprise to me, because I was under the impression that Pascal and C are very similar. (Though I hear the strings, at least, know their own size!)

I am fairly sure FPC protects against out of bounds access in some cases. I ported a Pascal game fairly verbatim to C for fun, and many segfaults later I realised it seemed to be relying on this behaviour of the language. Maybe I'm wrong, it's the only Pascal I've ever read.

Re: A guided intro to the Free Pascal language

#78

Post by gramie »

chinabot wrote: post #57
andai wrote: post #52

Earlier quoted context omitted.

You mention that Pascal is almost as safe as Rust. This comes as a great surprise to me, because I was under the impression that Pascal and C are very similar. (Though I hear the strings, at least, know their own size!)

Pascal is type safe and generally catches most errors at compile time, you can still create run-time errors such as indexes outside arrays but these will cause errors not bad return data. eg I use C a lot and find myself referencing array index [0] a lot, in pascal arrays starts at [1] if not specifically defined so I know this from experience, frustratingly I have a different problem in C which will either return ra…

I'm pretty sure that FreePascal and Delphi can do run-time bounds checking (it's a compile-time option).

Pascal also avoids buffer overrun errors on strings, because strings are dynamically resized as necessary.

You can also avoid having to free objects if you declare them as implementing a certain Interface (I forget the exact one). They will automatically be freed when the number of references drops to 0.

Re: A guided intro to the Free Pascal language

#79

Post by kwhitefoot »

chinabot wrote: post #57
andai wrote: post #52

Earlier quoted context omitted.

You mention that Pascal is almost as safe as Rust. This comes as a great surprise to me, because I was under the impression that Pascal and C are very similar. (Though I hear the strings, at least, know their own size!)

Pascal is type safe and generally catches most errors at compile time, you can still create run-time errors such as indexes outside arrays but these will cause errors not bad return data. eg I use C a lot and find myself referencing array index [0] a lot, in pascal arrays starts at [1] if not specifically defined so I know this from experience, frustratingly I have a different problem in C which will either return ra…

Pascal arrays can use any sub-range of an ordinal type as the index. You should define the distinct type of the index instead of using integers then you will get an exception if you attempt to use an out of range index.

Re: A guided intro to the Free Pascal language

#80

Post by jchw »

Peter5 wrote: post #51

Note for people who don't know much about FreePascal. It is a full-featured and very fast compiler. The resulting program is a rival for the best output of C/CPP compilers. It can be used in the style of simpler languages like Go and is almost as safe as Rust in a much faster manner. It has a great but old-looking IDE, Lazarus. It has been under active development for decades and is used for proper projects like: htt…

I don't believe you regarding "as safe as Rust." It's been a minute since I've messed with FreePascal, but as far as I know and can ascertain at a glance, it lacks any true modelling of memory safety to even match Go, and certainly not memory ownership to match Rust. It is surely possible to write correct programs in Pascal, and maybe even easier than C, but it would not be accurate to describe it as "as safe as Rust." It's not really even close...

Don't get me wrong, though. I do think Lazarus/FreePascal are underrated, but some of these claims are exaggerated. FPC generates good code, but on par with GCC/LLVM? I'd guess it's probably sitting closer to Go in terms of performance characteristics. More than good enough, but surely a ways away from the ridiculously complicated optimization systems in LLVM and GCC which aggressively vectorize, constant-fold, DCE, inline calls, interchange loops, and so forth.

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