F# autoindenter

let rec finder1 (work_list:string list list) (n_tab:int) (in_after_let:int) (in_list :int list) (else_list:int list) :(int*string) list=
    match work_list with
    |[]-> []
    |x::xs ->
        match x with
        |[] -> (0,"")::finder (xs) (0) (0) ([])  (else_list)
        |y::ys ->
            match y with
            |"let"->
                match last x with
                |"=" -> (n_tab, unisci_stringhe x)::finder (xs) (n_tab+1) (0) (add_element n_tab in_list) (else_list)
                |_ ->
                    match next_line xs with
                    |"in"->(n_tab, unisci_stringhe x)::finder (xs) (n_tab) (1) (in_list) (else_list)
                    |_->(n_tab, unisci_stringhe x)::finder (xs) (n_tab) (0) (in_list) (else_list)
            |"if"->(n_tab, unisci_stringhe x)::finder (xs) (n_tab+1) (in_after_let) (in_list) (n_tab::else_list)
            |"else"->
                match last x with
                |"else"->(first_int else_list, unisci_stringhe x)::finder (xs) (first_int else_list+1) (in_after_let) (in_list) (remove_first else_list)
                |_-> (first_int else_list, unisci_stringhe x)::finder (xs) (first_int else_list) (in_after_let) (in_list) (remove_first else_list)
            |"elif"->(first_int else_list, unisci_stringhe x)::finder (xs) (first_int else_list+1) (in_after_let) (in_list) (else_list)
            |"match"->(n_tab,unisci_stringhe x)::finder (xs) (n_tab) (in_after_let) (in_list) (else_list)
            |"|"->
                match last x with
                |"->" ->(n_tab,unisci_stringhe x)::finder (xs) (n_tab+1) (in_after_let) (in_list) (else_list)
                |_->
                    match next_line xs with
                    |"|"-> (n_tab,unisci_stringhe x)::finder (xs) (n_tab) (in_after_let) (in_list) (else_list)
                    |_ -> (n_tab,unisci_stringhe x)::finder (xs) (n_tab-1) (in_after_let) (in_list) (else_list)
            |"in"->
                match first_list xs with
                |[]->(penultimo in_list, unisci_stringhe x)::finder (xs) (n_tab) (in_after_let) (remove_first in_list) (else_list)
                |_->
                    match in_after_let with
                    |1->(n_tab,unisci_stringhe x)::finder (xs) (n_tab) (0) (in_list) (else_list)
                    |_->(first_int in_list,unisci_stringhe x)::finder (xs) (first_int in_list) (in_after_let) (remove_first in_list) (else_list)
            |_->(n_tab,unisci_stringhe x)::finder (xs) (n_tab-1) (in_after_let) (in_list)  (else_list)