My Life as a Forth Interpreter (1986) [pdf]

http://bit-player.org/wp-content/extras/bph-publications/CompLang-1986-04-Hayes-Forth.pdf

by waffle_ss • 12 years ago

73 19 12 years ago

bit-player.org

dimitar• 12 years ago

Wow, can someone explain this story? Its hard to follow if you are not a forth hacker.

davidw• 12 years ago

I think it has something to do with this:

http://globalnerdy.com/wordpress/wp-content/uploads/2007/09/...

nocoment2• 12 years ago

It looks like an introduction to FORTH via Kafka..

There is a nice browser interpreter here: http://forthfreak.net/jsforth80x25.html

you can start with: 1 1 + . (+ adds, . prints and this is clearly reverse polish notation)

FORTH is in essence an accumulator CPU like the 68000, except it has an easier abstraction to define new instructions (aka "Words") to act like the + or . above.

emeraldd• 12 years ago

Is that another term for a stack machine? I haven't heard of an accumulator cpu before ...

Someone2• 12 years ago

The tokens coming in are the tokens from the user's ("Him") input. The outer interpreter is what translates those tokens into actions to perform. The inner interpreter performs those actions.

In a Forth, both the inner and the outer interpreter are extremely simple. The story describes them in detail.

Outer interpreter: look up token in dictionary/dictionaries. If found, instruct inner interpreter to execute it by giving it the address of the function that the token describes. If not found, try interpreting the word as a number in the current base. If that succeeds, push the number on the stack. If it fails, signal an error and clear some state.

Inner interpreter: start reading at the address supplied. Recursively interpret every word read as address of another function until encountering a 'end of function' marker.

Leo Brodie's variant of this story doesn't use the terms inner and outer interpreter because it was written before the names were invented, but it may be instructive, anyways: http://www.forth.com/starting-forth/sf1/sf1.html

raverbashing• 12 years ago

So the inner interpreter is a VM of some sort?

Outer interpreter looks like exactly that, an interpreter (as opposed to a compiler)

etfb• 12 years ago

For context: the Computer Language magazine in the 1980s had a tradition of April Fools editions. This is from one of them, before they got too serious, changed their name to Software Development magazine, and blazed the way for Dr Dobbs into oblivion.

TazeTSchnitzel• 12 years ago

That was brilliant. Now, how about "My Life as a Haskell Interpreter"?

eru• 12 years ago

That would be interesting. And the cliff from Outer Interpreter to Compiler (instead of Inner Interpreter) would be even steeper.

brianobush• 12 years ago

anyone have a copy? link is dead.

kevinchen• 12 years ago

Scribd seems to have it cached. Link reproduced here for convenience: http://www.scribd.com/doc/212732047/Untitled?secret_password...

shellehs• 12 years ago

I'm too late. It's 403 now.

You don't have permission to access /wp-content/extras/bph-publications/CompLang-1986-04-Hayes-Forth.pdf on this server.

The site shows.

mthq• 12 years ago

The site owner thinks he is being DDOS'ed: http://bit-player.org/2014/net-pests/

bit-player2• 12 years ago

I'm the site owner. It's open again, temporarily. Somebody's script has multiple machines (many are EC2 instances) downloading the same file many times per second. That's not something I want to encourage.

zem• 12 years ago

very nicely done indeed.

bit-player2• 12 years ago

Apologies to the HN community.

I'm the author of the story linked to here. I'm also the jerk who pulled it off the web when I thought my site was getting the DDoS treatment. Mea culpa.

My Life as a Forth Interpreter (1986) [pdf]

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