How deeply does Clojure: The Essential Reference cover fn??

Defines the predicate's true-or-false behavior but does not detail its implementation or classify other callable values.

Fn?

As explained in Clojure: The Essential Reference

fn? is a Clojure predicate that returns true when its argument is a Clojure function.

Use `fn?` to check whether a value is a Clojure function. It returns `true` for a function and `false` for a non-function value. Functions created with `fn` are first-class values: they can be bound locally or passed as arguments. section 2.1.2

Checking function values

```clojure (fn? (fn [x] x)) ; true (fn? (partial + 1)) ; true (fn? 42) ; false ``` `partial` generates a new function, so its result can be checked just like a function written with `fn`. section 2.1.2 section 2.2.8

How Clojure: The Essential Reference covers it

Cover of Clojure: The Essential Reference

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Related concepts

defnused by · defn is a Clojure macro that defines a named function and binds it to a Var in the enclosing namespace.
future?used by · future? is a Clojure predicate that reports whether a value is a future reference.
partialalternative to · partial is a callable factory that returns a new function with specified arguments pre-applied to an existing function, leaving the remaining arguments variable.
functionproduces · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
destructureuses · destructure is a Clojure function that transforms a binding form and an expression into bindings implementing destructuring.
locals clearinguses · Locals clearing is a compiler optimization that nulls references held by a function after one-time execution so the referenced resources can be reclaimed.

This explainer was generated by Manning's knowledge graph from the text of Clojure: The Essential Reference. The section links point to the parts of the book it draws on.