Portable Forth Environment

Hey, so I fell down a bit of a rabbit hole last night with Portable Forth Environment—that Forth IDE for Mac I mentioned I'd been curious about. You know I've got this weird fascination with old-school languages, and Forth's been on my list forever. Simple stack-based stuff, interactive, runs close to the metal—sounded perfect for tinkering.

First impression: it's actually a proper native Mac app, not just a terminal wrapper. Clean editor, real-time stack display, the works. But of course, I immediately hit the wall that defines Forth for beginners: I had no idea what the hell I was doing with the stack.

What I tried first (and why it failed hilariously):

Opened the interactive console, figured I'd start simple. Typed 5 3 + . — that's "push 5, push 3, add, print" in Forth. It printed 8. Great. Feeling confident, I tried something slightly less trivial: 10 2 * 5 + .. Expected 25. Got 20. Stared at it for a minute. Realized the order was wrong—I'd done 10 2 * (20), then pushed 5, then + added the 5 to the 20. But I'd wanted 2 * 5 first. Forth doesn't care about your intentions; it just does exactly what the stack says. My brain, trained on infix notation, kept tripping over this.

What I eventually figured out:

Forth is brutally honest. If you mess up the stack order, you get the wrong answer—no hand-holding. The trick is to think in terms of "what's on the stack right now" at every step. The IDE's interactive stack display saved me here—I could see the stack contents after each word, which made the order crystal clear. For 10 2 * 5 +, the stack went: 10, then 10 2, then after * it was 20, then 20 5, then + gave 25. Once I could see it, it clicked.

What actually helped (the stuff I wish I'd known first):

1. Used the step debugger. PFE has this "execute word-by-word" mode. I stepped through a simple calculation and watched the stack change in real time. Game-changer for understanding.
2. Realized the word browser shows you definitions. I kept typing + and assuming it worked like other languages. Looking at its actual definition (: + ( n1 n2 -- sum ) ...) made the stack effect explicit.
3. Found the tutorial projects. There's a "Calculator" example that walks through building a reverse-Polish calculator. Running that and seeing how the words build on each other taught me more than any guide.

Once I got my head around the stack, I actually started enjoying it. Forth is weirdly elegant—you build complexity by defining small words that each do one thing, then compose them. I wrote a tiny word : SQUARE DUP * ; (duplicates the top number, multiplies) and then used it in : SUM-OF-SQUARES SQUARE SWAP SQUARE + ;. The language practically disappears; you're just manipulating numbers on a stack.

A couple of other things I stumbled on:

• The memory analyzer is great for seeing how your dictionary grows. Forth compiles words as you define them, so you can see the exact memory footprint.
• You can call macOS system frameworks directly—there's an example that opens a Cocoa window. Wild to see Forth talking to Objective-C APIs.
• The profiler showed me that a recursive Fibonacci I wrote was absurdly slow. Rewrote it iteratively with stack manipulation and it flew. Performance introspection is built-in.
• I found this page that explains stack notation—the ( n1 n2 -- sum ) style suddenly made sense after seeing it in context.

Checklist for next time (so I don't repeat mistakes):

1. Always check the stack effect of a word before using it. The word browser shows this instantly.
2. Use the stack display constantly, especially when learning. It's like training wheels for your mental stack model.
3. Start with the example projects. The "Reverse Polish Calculator" tutorial is perfect for understanding the flow.
4. If something behaves wrong, step through it word-by-word. The debugger exposes exactly where your stack logic fails.
5. Remember that Forth compiles as you go—; finishes a definition, but you can test words immediately after defining them.

Anyway, I'm actually hooked now. It's like programming in a different dimension—no variables, no precedence rules, just a stack and words that transform it. If you ever want to feel like you're learning to code all over again, give it a shot. Let me know if you try it—curious if the stack clicks for you faster than it did for me.