Writing a Forth in Haskell

Re:Writing a Forth in Haskell by kazinator on Thursday June 08, 2017 @07:18PM (#14517939)

Lisp's abstract model doesn't use stacks to pass arguments. Arguments are just lexical variables and they live in environments like other lexical variables: completely foreign stuff to Forth. Environments often have to survive the termination of a lexical scope's execution; it is required when a closure has escaped. So things can't even be compiled to a stack-based machine, using a "pop everything when returning" strategy: only in some cases.

(ANSI) Lisp function calls are safe w.r.t. wrong number of arguments, and support optional and variadic arguments also. This is true of compiled code without source: when we load someone's compiled file and call a function in it with the wrong number of arguments, it is diagnosed.

Forth and Lisp are so miles apart, that I have to scratch my head why a comparison comes up in discussion from time to time.

(It is pretty much always from someone who uses Forth and doesn't know Lisp (or, worse, anything that isn't Forth). "Hey, I heard Lisp is also interactive and meta-programmable, so it must just be a Forth with postfix switched to prefix and parentheses added ...").

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Re:Writing a Forth in Haskell by lacampbell on Friday June 09, 2017 @08:32AM (#14520896)

I had this dumb idea of actually evaluating LISP in a forth inspired way. It would be a stack of subroutine/accumulator pairs. so given

    (+ 1 2 3)

"(" would pop an pair on a stack, + would set its subroutine, and 1 2 3 would be fed to the subroutine and accumulate a value. when ) is encountered, the data is fed into the subroutine/accumulator pair lower on the stack, so you could still have nesting.

Horribly inefficient, but I thought the idea was neat. I'm sure I'm not the first to think of it though.

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Re:Writing a Forth in Haskell by agumonkey on Monday June 12, 2017 @03:54PM (#14540510)

some antique famous lisper (Henry .. forgot last name) did write a linear lisp that works by stack evaluation. From the few that I grasped, since everything is mostly duped, it's like a new value each time; free borrowing ?

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Re:Writing a Forth in Haskell by evincarofautumn on Friday June 09, 2017 @07:48PM (#14525411)

Higher-level concatenative languages like Factor do feel somewhat Lisp-like because most code is structured with quotations and combinators. But typical Forth isn’t very much like typical Factor or Joy at all, even though they’re all nominally concatenative.

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