Leetcode wildcard matching solution in F#. https://leetcode.com/problems/wildcard-matching/

match.fs

type pattern =
  | Char of char * pattern 
  | Any of pattern 
  | Wildcard of pattern 
  | End

let parsePattern (str: string) = 
   let str = [for s in str do s]
   let folder c pat = 
       match c with 
       | '?' -> Any pat 
       | '*' -> Wildcard pat 
       | c -> Char (c, pat)
   List.foldBack folder str End

let matches c = function 
    | Char (x, _) -> x = c
    | Any _ -> true 
    | Wildcard _ -> true 
    | End -> false 

let rec is_match str pat = 
  match str, pat with 
  | c :: str, Char (x, pat) -> c = x && is_match str pat 
  | _any :: str, Any pat -> is_match str pat 
  | [], Wildcard End -> true
  | c :: str, Wildcard pat -> is_match (c :: str) pat || is_match str (Wildcard pat)
  | _c :: _str, End -> false 
  | [], End -> true
  | [], Char _ | [], Any _ | [], Wildcard _ -> false 

let isMatch (str: string) pat = 
    is_match [for s in str do s] (parsePattern pat)