Hang when dealing with some pieces of code

[linkpy]

(register-type MyType)

(defmodule MyType
  (register init (Fn [] MyType))
  (register delete (Fn [&MyType] ()))
  (register copy (Fn [&MyType] MyType))
)

(deftype MyWrapper [inner MyType])

(defmodule MyWrapper
  (defn delete [w]
    (MyType.delete (MyWrapper.inner &w))))

(defn main []
  (let [v (MyWrapper.init (MyType.init))]
    (IO.println "in let")))

This code, when doing (load "test.carp") hangs and consume all of my memory (16Gb). But, if i do (MyType.delete (MyWrapper.inner w)) (removing the &) then it loads correctly.

I have no idea how i can debug this (i have no knowledge of Haskell) so don't hesitate to ask for more info.

[hellerve]

Hey! Thanks for reporting this!

I’m assuming that Carp chokes on the redefinition of an autogenerated delete function (which, in my opinion, should be possible). Maybe @eriksvedang can provide more insight into this!

[linkpy]

I'm renaming that issue because I encountered it with a piece of code not using references at all :

(deftype MyType [v Int])

(defmodule MyType
  (sig delete (Fn [MyType] ()))
  (defn delete [o]
    (do
      (IO.println "in delete")
      ())))

(defn main []
  (let [v (MyType.init 0)]
    (IO.println "in let")))

Doing (load "test.lisp") hangs. I tried to input each line into the REPL, and it hangs for the main function declaration.

When I try reordering the statements : deftype, then defn main then defmodule, the REPL doesn't hang anymore, but the compile fails :

out/main.c:8813:9: warning: implicit declaration of function 'MyType_delete' is invalid in C99 [-Wimplicit-function-declaration]
        MyType_delete(v);
        ^
1 warning generated.
/usr/bin/ld: /tmp/main-f81b52.o: in function `main':
/home/linkie-pi/Documents/devel/carp/gdnative-carp/out/main.c:8813: undefined reference to `MyType_delete'
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)
carp: callCommand: clang -fPIC -lm -g out/main.c -o "out/Untitled"  -I/home/linkie-pi/Documents/Carp/core/   (exit 1): failed

I obtain the same error when using a file with the reordered code. When i tried with defn main as the first definition in the file, the parse fails due to MyType.init not declared and I guess it's to be expected.

Some more info that could be useful (based on the example given in that comment) :

• When the main doesn't use MyType, the hang does not happen (for example, (IO.println "test") as the main's body.
• I wanted to check if let wasn't causing the issue, so i tried (MyType.delete (MyType.init 0)) as the main's body code. Carp hangs with that code.
• Renaming delete to my-delete doesn't make main to hang.

[scolsen]

I've encountered this before. I could be wrong, but I think the same hang happens for sumtypes + modules too.

[scolsen]

I suspect this might have to do with some of the eval or constraint generation loops or solving loops since it seems to have some kind of relationship with struct/sumtypes.

Or it has to do with lookups happening somewhere that enter in a loop somehow 🤔