Except except

Returns the items in the first collection that are not in the second collection.

Basic Usage

↪ (except [1 2 3 4 5] [2 4])
[1 3 5]
↪ (except ['a 'b 'c] ['a 'c])
[b]
↪ (except [1 2 3] [5 6 7])
[1 2 3]

Scalar Except

↪ (except [1 2 3 4 5] 3)
[1 2 4 5]
↪ (except ['a 'b 'c] 'b)
[a c]

Handling Duplicates

↪ (except [1 1 2 2 3] [1 3])
[2 2]
↪ (except ['a 'a 'b 'c 'c] ['a 'c])
[b]

Info

• Returns elements from the first collection that don't exist in the second
• Can use a scalar as the second argument to remove a single value
• Duplicates are preserved in the result (unlike distinct)
• If an element appears multiple times in the first collection but is excluded, all occurrences are removed
• Empty collections are handled gracefully: (except [] x) returns [], (except x []) returns x

Tip

Use except to filter out unwanted values from a collection while preserving duplicates