Predicate

Definitions

1. A function that takes an input and returns a boolean (true/false). Used extensively in filtering, searching, and conditional logic. In SQL it is the WHERE clause condition; in functional programming, predicates are passed to filter(), find(), and every().

   In plain English: A yes-or-no question you ask about each item in a list — 'is this user active?' 'is this number even?' — used to filter or test data.

   Example: "Pass a predicate to filter: users.filter(u => u.age >= 18) keeps only adults."

Related Terms

• Algorithm
• Boolean
• Clause
• Discriminated Union
• Effect System
• If-Else
• Option Type
• Pattern Matching
• Lens