-
In PureScript or OCaml, you can use open variant types to do this flawlessly
Yes!! Polymorphic variants are incredible
-
Related paper: https://lobste.rs/s/9akqxf/catch_me_if_you_can
-
-
-
In fact, you can consider exceptions of
exnto be a special case of the open, or extensible variant! See https://caml.inria.fr/pub/docs/manual-ocaml/extn.html#sec266 for more details. -
-
-
-
Another thing I thought was nice to mention: row polymorphism.
In row polymorphism, variants are open by default. I’ve been toying with writing my own implementation but this one has a nice readme explaining pretty well how it works.
https://github.com/willtim/Expresso#variants
The reason given for variant literals being open by default is usually to do error handling and only expose our current problems.
-
Polymorphic variants in OCaml work by row polymorphism - this paper introduced the algorithm and resulted in the ocaml implementation. Good luck with the implementation! It’s my favorite type system feature :)
-
-
-
The usual stuff: awesome with lots of tabs, some poorly written widgets, and a relatively minimal vim with the excellent merlin. xterm for minimal typing latency. Other stuff in the background: cmus, unbound, redshift, neomutt. The laptop is a heavyweight (5 kg) Clevo P775 with desktop components and a 3k screen.
-
I’ve never seen that one image in the Game of Life article. That looked wild. Do you have a link to that implementation and its parameters so we can replicate it?
-
Looks like this gun: http://www.conwaylife.com/w/index.php?title=P416_60P5H2V0_gun
Rendered: https://copy.sh/life/?pattern=p41660p5h2v0gun
And if you have some time to waste: http://www.conwaylife.com/wiki/Category:Patterns_with_1000_or_more_cells
-
I saw some experimentation back when I looked at it with gliders or simple patterns. I didnt know they’d taken it this far with these complex designs. Pretty amazing. Thanks for the link.
-
-
-
Fun facts:
- All instructions use modrm encoding for encoding memory operands, except for A0/A1/A2/A3, where the address is a constant encoded immediately after the instruction (“moffs”).
- x86 has a single-byte encoding for
INC esp(increment stack pointer by one). - x86 has a single-byte encoding for BCD-arithmetic. For example: AAA - ASCII Adjust After Addition.
-
POP [ptr](pop a dword from the stack and move it to the specified address in memory) updatesespbefore resolvingptr(which can containesp). In some sense it mixes decoding of the instruction and execution. -
LEA reg, [ptr]is an instruction that computesptrand stores it in a register without referencing memory. Pointer arithmetic is very flexible in x86, being able to add a register with a shift, another register and a constant offset. For example, it can encodea = b + c -1in a single instruction.LEAis also the only instruction that fails when encoded with a register operand (becauseLEA reg1, reg2is invalid) but never fails when encoded with a memory operand. - There are two ways to encode
OP reg1, reg2for most instructions. -
XCHG eax, ris encoded as0x90+r,NOPis0x90orXCHG eax, eax. - Most arithmetic instructions also compute the parity flag, which is the parity of the lowest byte of the result.
- Most arithmetic instructions also compute the adjust flag, which is set when an overflow happens from the 4th bit of the result.
- Due to a bug in Windows NT, CPUID reports some bits differently depending configuration registers. Search for “bug” in http://sandpile.org/x86/cpuid.htm.
-
-
-
I was hoping for an interface where I can see the registers, flags, memory, etc. in real time along with the .text history, similar to this.
-
-
it’s be nice, for pdf papers, to add a bit of context to help people decide whether to read or not.
Good idea.
From the abstract: “This is the year 2008 and ML-style exceptions are everywhere. Most modern languages, whether academic or industrial, feature some variant of this mechanism. Languages such as Java even feature static coverage-checking for such exceptions, something not available for ML languages, at least not without resorting to external tools. In this document, we demonstrate a design principle and a tiny library for managing errors in a functional manner, with static coverage-checking, automatically-inferred, structurally typed and hierarchical exceptional cases, with a reasonable run-time penalty. Our work is based on OCaml and features monads, polymorphic variants, compile-time code rewriting and trace elements of black magic.”