Advent of Code 2015, Day 1, Part 1 in North

2015d1.4th

\ Small example filename to the stack
"./d1.txt"

\ Read the file (as string) to stack
read-file

\ Define custom factor
\ Input: count char*
\ Output: [count, "\n"]
: final-floor

\ Done if we only have count and newline char
[ab]? if done

\ Swap top two
[ab*]->[ba*]

\ Is top character a close-paren? (No popping here because it's a pattern)
")" [aa*]?

\ Remove the character we pushed for the check
[bivc*]->[bcv*]

\ Decrement count if they're the same
if decr

\ Swap count and paren again
[ab*]->[ba*]

\ If paren is open paren, increment (`=` check pops)
"(" = if incr

\ Recurse
again
;

\ Put each character of the string onto the stack as a single-char string
splat-string

\ Our starting floor is 0
0

\ Invoke user-defined factor
final-floor

\ Fail if we don't get back the expected floor
-3 = assert