Pangram checker

You are encouraged to solve this task according to the task description, using any language you may know.
A pangram is a sentence that contains all the letters of the English alphabet at least once.

For example:   The quick brown fox jumps over the lazy dog.



Task

Write a function or method to check a sentence to see if it is a   pangram   (or not)   and show its use.



Related tasks

   determine if a string has all the same characters
   determine if a string has all unique characters


fun to_locase s = implode ` map (c_downcase) ` explode s
 
fun is_pangram 
	(h :: t, T) = 				 
		let 
			val flen = len (filter (fn c = c eql h) T)
		in
			if (flen = 0) then
				false
			else
				is_pangram (t, T)
		end
|	([], T) = true 
| 	S = is_pangram (explode "abcdefghijklmnopqrstuvwxyz", explode ` to_locase S)
 
fun is_pangram_i 
	(h :: t, T) = 				 
		let 
			val flen = len (filter (fn c = c eql h) T)
		in
			if (flen = 0) then
				false
			else
				is_pangram (t, T)
		end
|	([], T) = true 
| 	(A,S) = is_pangram (explode A, explode ` to_locase S)
 
fun test (f, arg, res, ok, notok) = if (f arg eql res) then ("'" @ arg @ "' " @ ok) else ("'" @ arg @ "' " @ notok)
fun test2 (f, arg, res, ok, notok) = if (f arg eql res) then ("'" @ ref (arg,1) @ "' " @ ok) else ("'" @ ref (arg,1) @ "' " @ notok)
 
;
println ` test (is_pangram, "The quick brown fox jumps over the lazy dog", true, "is a pangram", "is not a pangram"); 
println ` test (is_pangram, "abcdefghijklopqrstuvwxyz", true, "is a pangram", "is not a pangram"); 
val SValphabet = "abcdefghijklmnopqrstuvwxyzåäö";
val SVsentence = "Yxskaftbud, ge vår wczonmö iq hjälp";
println ` test2 (is_pangram_i, (SValphabet, SVsentence), true, "is a Swedish pangram", "is not a Swedish pangram"); 
 