Getting errors while compiling

//! library List

struct pair
    integer value
    pair next

    static method cons takes integer value, pair next returns pair
            local pair p = pair.create()
        set p.value = value
        set p.next = next
        return p
    endmethod

    method copy takes nothing returns pair
        if this.next == 0 then
            return pair.cons(this.value,0)
        else
            return pair.cons(this.value,this.next.copy())
        endif
    endmethod

    //remove recursion
    static method Destroy takes pair p returns nothing
        local pair next = p.next
        call pair.destroy(p)
        if p.next != 0 then
            call pair.Destroy(next)
        endif
    endmethod
endstruct

struct list
    pair l
    static method Create takes nothing returns list
        local list s = list.create()
        set s.l = 0
        return s
    endmethod
    method push takes integer value returns nothing
        set this.l = pair.cons(value,this.l)
    endmethod
    method pop takes nothing returns nothing
        if this.l != 0 then
            set this.l = this.l.next
        endif
    endmethod
    method peek takes nothing returns integer
        return this.l.value
    endmethod
    method isempty takes nothing returns boolean
        return this.l == 0
    endmethod
    method shuffle takes nothing returns nothing
        local pair array lst
        local integer n = 0
        local pair p = this.l
        local integer i = 0
        local integer swapwith
        loop
            exitwhen p == 0
            set lst[n] = p
            set n = n + 1
            set p = p.next
        endloop

        loop
            exitwhen i >= n
            set swapwith = GetRandomInt(i,n-1)
            //swap ith with n-1th
            //need to include i so that every element can end up in every position
            set p = lst[swapwith]
            set lst[swapwith] = lst[i]
            set lst[i] = p
            set i = i + 1
        endloop

        set i = 0
        loop
            exitwhen i >= n-1
            set lst[i].next = lst[i+1]
            set i = i + 1
        endloop
        set lst[i].next = 0
        set this.l = lst[0]
    endmethod
    //fine for acyclic
    method copy takes nothing returns list
        return this.l.copy()
    endmethod

    static method Destroy takes list l returns nothing
        call pair.Destroy(l.l)
        call list.destroy(l)
    endmethod
endstruct

//! endlibrary