This is one way to determine if a sentence is a pangram using RETRO.
First, define a string containing the alphabet:
Then a blank string of the same length for the test data:
Now a word to do the actual test.
Breaking this down, the first line:
' &TEST #26 copy
Copies a blank string over the TEST string. Then:
s:to-lower [ c:letter? ] s:filter
Converts the string to lowercase and strips out anything that's not a letter. Then a quick iteration over each character:
[ dup $a - &TEST + store ] s:for-each
Reduces the letter to an index into the TEST string and stores the letter at the appropriate spot. And finally:
&TEST &FULL s:eq? ;
Just compares the TEST and FULL strings to get the result.
Here's a couple of test cases: