Unexpected repl behaviour

[andrewnc]

I have encountered this behaviour a few times when using BQN. I will enter an expression, but instead of an output OR an error, I will see what seems to be a call graph.

For example,
{𝕩⍟0} 3 ->

v0=e[1];if(v0===null)err();
v1=e[5];if(v1===null)err();
v2=e[2];if(v2===null)err();
v0=call(v1,v0,v2);
v1={e:e,p:6};
v0=set(1,v1,v0);

v0=O[21];
v1={e:e,p:7};
v0=set(1,v1,v0);
v1={e:e,p:8};
v0=set(1,v1,v0);

v0=e[6];if(v0===null)err();
v1=O[21];
v2=e.p[66];if(v2===null)err();
v3=D[121](e);
if(v2.m!==2)err();v1=v2(v3,v1);
v0=call(v1,v0);

v0=e[1];if(v0===null)err();
v1={e:e,p:9};
v0=set(1,v1,v0);

v0=D[122](e);
v1={e:e,p:10};
v0=set(1,v1,v0);

v0=e[7];if(v0===null)err();
v1=e[10];if(v1===null)err();
v2=e.p[1];if(v2===null)err();
v3=e[4];if(v3===null)err();
v4=e[2];if(v4===null)err();
v2=((f,g,h)=>(x,w)=>call(g,call(h,x,w),has(f)?call(f,x,w):f))(v4,v3,v2);
if(v1.m!==1)err();v1=v1(v2);
v0=call(v1,v0);
v1={e:e,p:11};
v0=set(1,v1,v0);

v0=e[8];if(v0===null)err();
v1=e.p[55];if(v1===null)err();
v0=call(v1,v0);
v1=e[10];if(v1===null)err();
v2=e.p[1];if(v2===null)err();
v3=e.p[119];if(v3===null)err();
v4=e[4];if(v4===null)err();
if(v3.m!==1)err();v3=v3(v4);
v4=e[2];if(v4===null)err();
v2=((f,g,h)=>(x,w)=>call(g,call(h,x,w),has(f)?call(f,x,w):f))(v4,v3,v2);
if(v1.m!==1)err();v1=v1(v2);
v0=call(v1,v0);
v1={e:e,p:12};
v0=set(1,v1,v0);

v0=e[6];if(v0===null)err();
v1=O[21];
v2=e.p[66];if(v2===null)err();
v3=e.p[3];if(v3===null)err();
v4=e[11];if(v4===null)err();
v5=e[12];if(v5===null)err();
v4=list([v4,v5]);
if(v3.m!==1)err();v3=v3(v4);
v4=e.p[115];if(v4===null)err();
v5=O[21];
v6=e.p[7];if(v6===null)err();
v7=e.p[48];if(v7===null)err();
if(v6.m!==2)err();v5=v6(v7,v5);
v3=((f,g,h)=>(x,w)=>call(g,call(h,x,w),has(f)?call(f,x,w):f))(v5,v4,v3);
v4=e.p[115];if(v4===null)err();
v5=e.p[42];if(v5===null)err();
v3=((f,g,h)=>(x,w)=>call(g,call(h,x,w),has(f)?call(f,x,w):f))(v5,v4,v3);
if(v2.m!==2)err();v1=v2(v3,v1);
v0=call(v1,v0);
return v0;}

and 2◶"abcdef" ->

v0=e[1];if(v0===null)err();
v1=D[120](e);
v2=e[5];if(v2===null)err();
v3=e.p[115];if(v3===null)err();
v4=e[1];if(v4===null)err();
v5=e[4];if(v5===null)err();
v6=e[2];if(v6===null)err();
v4=call(v5,v4,v6);
v2=call(v3,v2,v4);
if(v1.m!==1)err();v1=v1(v2);
v2=e[2];if(v2===null)err();
v0=call(v1,v0,v2);
return v0;}

Am I missing a simple symbol for echoing / printing in these situations? I would love some clarity here.

[dzaima]

It's printing the source code of the function. The JS BQN compiler converts your code to JS code to be evaluated, and it seems there's nothing preventing that source code from just being printed. As a simpler example, try just !.

[andrewnc]

Ok, fascinating, is this a user error on my end?

[dzaima]

There's no reason to not allow printing functions, whatever that ends up as being. It could of course be made to print something nicer, but that's probably of relatively low priority compared to other things about the language.

[andrewnc]

Oh! I see, I am trying to call the functions, is there something obvious I'm missing to initiate that call?

[dzaima]

{𝕩⍟0} 3 is equivalent to 3⍟0, which is syntactically like 3⍣0 in APL - you aren't calling anything, you end up with a 2-modifier (dyadic operator in APL terms), derived to a function. Similarly for 2◶"abcdef" - it's again just deriving a 2-modifier

[andrewnc]

That makes sense, I'm coming from J and am still getting the hang of things.

How do I repeat 3 "0"s and select the 2th item respectively?

[mlochbaum]

Those would be 3⥊0 and 2⊑"abcdef". See Indices for more discussion on Select (⊏) versus Pick (⊑) though.

[dzaima]

As a quick test, anything circled is a 2-modifier (aka conjunction; ⌽⍉ are exceptions and are functions similar to APL), and superscripts (˜¨˘⁼⌜´`) are 1-modifiers (adverbs); see this

[andrewnc]

Ok perfect! I got my simple example working

{𝕩‿𝕩 ⥊ 1∾ 𝕩⥊0} 3

Thank you both for the help.

[mlochbaum]

The non-array part of formatting was just casting to a string with ""+x (it has to be implemented in Javascript, since there isn't a way to find a scalar's type from BQN yet). I've improved it to detect primitives and infinities, and use ¯ for a minus sign. For non-primitive functions and modifiers, it just prints the type, for example *1-modifier*. Since they're anonymous functions, deconstructing them to get better output would be difficult with the current VM. But at least there are no raw function printouts any more.