Help with costume stiching

[starbox614]

in this project, I made a block that takes a chunk, and outputs a stitched costume for it. the chunk is an 18x24 table, where each item in the table is either nothing, a zero, or a dictionary list where one of the keys is "texture". the value of that key is a 20x20 pixel costume. the block should report all of the costumes stitched together according to their order in the table, with the non-lists replaced by a transparent 20x20 costume. unfortunately, the block is too slow, and it slows down everything else. can it be made faster? also, how could this be implemented in a JS function?
Thank you!

examples

an example of a chunk:

one of the blocks in the chunk:
(these are what the sublists in the above table are, although they may have different data)

a visualization of the costumes in the chunk:
(this is not a piece of data that the program can actually access, it is just for visualization purposes)

the result costume when given the above example chunk as input:

(the example chunk is stored in the variable "debug var" in the project)

current code

[bh]

I haven't read this carefully, but one little thing is that instead of RESHAPE (LIST (LIST 0 0 0 0))... you can just say RESHAPE 0 .... The reported shape is determined entirely by the dimension numbers, not by the structure of the input data.

[starbox614]

ok. that makes sense

[starbox614]

Why do stacked compiled HOFs break?

[bh]

@starbox614

Why do stacked compiled HOFs break?

Could you give an example?

[starbox614]

this works:

but:

and

[bh]

Oh. Only certain first-input functions can be compiled in the HOFs. But if it can't be compiled it should just work as a non-compiled HOF, not error out. Thanks for reporting this.