don't break puzzles with leading spaces

min-steps.scm

@@ -1,6 +1,8 @@
 #! /usr/bin/env guile -e main -s
 !#
 
+;; TODO: make this a module
+
 (use-modules (srfi srfi-1)
              (srfi srfi-9 gnu)
              (srfi srfi-11)
@@ -107,13 +109,27 @@
 
 ;; board = (player-pos (wall goal box)-bitsets)
 (define (string->board s)
-  ;; string-trim-both instead of filter (compose not string-null?) keeps internal
-  ;; blanks while removing (almost always) useless leading and trailing blanks
-  (define lines (list->vector (string-split (string-trim-both s) #\newline)))
+  ;; string-trim alone doesn't work because e.g.
+  ;;   ###
+  ;; ###.#
+  ;; #@ $#
+  ;; #   #
+  ;; #####
+  ;; becomes
+  ;; ###
+  ;; ###.#
+  ;; #@ $#
+  ;; #   #
+  ;; #####
+  ;; which is just no good
+
+  (define lines (list->vector
+                 (string-split (string-trim-both s (lambda (c) (eqv? c #\newline)))
+                               #\newline)))
   (define widths (vector-map (lambda (_ line) (string-length line)) lines))
   (define width (apply max (vector->list widths)))
   (define height (vector-length lines))
-  
+
   (define player-x #f)
   (define player-y #f)
 
@@ -276,9 +292,6 @@
 "))
 
 
-(define (main . args)
+(define (main args)
   (define-values (cost node) (min-steps (string->board (get-string-all (current-input-port)))))
   (format #t "~a\n~a\n" cost node))
-
-;; TODO: lol i have immutable board movement, so just make this actually playable
-;; with super easy undo lol