A predicate function returns a boolean true or false, and it's name ends with a ?. Ran against Clojure 1.10.0.
({:ns clojure.string,
:predicates
({:fn ends-with?, :arglists ([s substr])}
{:fn starts-with?, :arglists ([s substr])}
{:fn includes?, :arglists ([s substr])}
{:fn blank?, :arglists ([s])})}
{:ns clojure.core,
:predicates
({:fn decimal?, :arglists ([n])}
{:fn contains?, :arglists ([coll key])}
{:fn every?, :arglists ([pred coll])}
{:fn qualified-keyword?, :arglists ([x])}
{:fn satisfies?, :arglists ([protocol x])}
{:fn seq?, :arglists ([x])}
{:fn fn?, :arglists ([x])}
{:fn vector?, :arglists ([x])}
{:fn thread-bound?, :arglists ([& vars])}
{:fn any?, :arglists ([x])}
{:fn isa?, :arglists ([child parent] [h child parent])}
{:fn boolean?, :arglists ([x])}
{:fn char?, :arglists ([x])}
{:fn some?, :arglists ([x])}
{:fn inst?, :arglists ([x])}
{:fn future-done?, :arglists ([f])}
{:fn simple-symbol?, :arglists ([x])}
{:fn pos?, :arglists ([num])}
{:fn sequential?, :arglists ([coll])}
{:fn neg?, :arglists ([num])}
{:fn reduced?, :arglists ([x])}
{:fn float?, :arglists ([n])}
{:fn set?, :arglists ([x])}
{:fn reversible?, :arglists ([coll])}
{:fn bound?, :arglists ([& vars])}
{:fn map?, :arglists ([x])}
{:fn volatile?, :arglists ([x])}
{:fn var?, :arglists ([v])}
{:fn empty?, :arglists ([coll])}
{:fn string?, :arglists ([x])}
{:fn uri?, :arglists ([x])}
{:fn double?, :arglists ([x])}
{:fn map-entry?, :arglists ([x])}
{:fn int?, :arglists ([x])}
{:fn associative?, :arglists ([coll])}
{:fn keyword?, :arglists ([x])}
{:fn even?, :arglists ([n])}
{:fn tagged-literal?, :arglists ([value])}
{:fn extends?, :arglists ([protocol atype])}
{:fn indexed?, :arglists ([coll])}
{:fn counted?, :arglists ([coll])}
{:fn future?, :arglists ([x])}
{:fn zero?, :arglists ([num])}
{:fn simple-keyword?, :arglists ([x])}
{:fn not-every?, :arglists ([pred coll])}
{:fn class?, :arglists ([x])}
{:fn future-cancelled?, :arglists ([f])}
{:fn neg-int?, :arglists ([x])}
{:fn sorted?, :arglists ([coll])}
{:fn nil?, :arglists ([x])}
{:fn instance?, :arglists ([c x])}
{:fn bytes?, :arglists ([x])}
{:fn record?, :arglists ([x])}
{:fn identical?, :arglists ([x y])}
{:fn ident?, :arglists ([x])}
{:fn qualified-ident?, :arglists ([x])}
{:fn true?, :arglists ([x])}
{:fn reader-conditional?, :arglists ([value])}
{:fn integer?, :arglists ([n])}
{:fn special-symbol?, :arglists ([s])}
{:fn ratio?, :arglists ([n])}
{:fn delay?, :arglists ([x])}
{:fn ifn?, :arglists ([x])}
{:fn nat-int?, :arglists ([x])}
{:fn chunked-seq?, :arglists ([s])}
{:fn distinct?, :arglists ([x] [x y] [x y & more])}
{:fn pos-int?, :arglists ([x])}
{:fn odd?, :arglists ([n])}
{:fn uuid?, :arglists ([x])}
{:fn false?, :arglists ([x])}
{:fn list?, :arglists ([x])}
{:fn simple-ident?, :arglists ([x])}
{:fn rational?, :arglists ([n])}
{:fn realized?, :arglists ([x])}
{:fn number?, :arglists ([x])}
{:fn not-any?, :arglists ([pred coll])}
{:fn qualified-symbol?, :arglists ([x])}
{:fn seqable?, :arglists ([x])}
{:fn symbol?, :arglists ([x])}
{:fn coll?, :arglists ([x])})}
{:ns clojure.core.specs.alpha,
:predicates
({:fn even-number-of-forms?, :arglists ([forms])})}
{:ns clojure.spec.alpha,
:predicates
({:fn inst-in-range?, :arglists ([start end inst])}
{:fn valid?, :arglists ([spec x] [spec x form])}
{:fn regex?, :arglists ([x])}
{:fn int-in-range?, :arglists ([start end val])}
{:fn spec?, :arglists ([x])}
{:fn ?, :arglists ([pred-form])}
{:fn invalid?, :arglists ([ret])}
{:fn check-asserts?, :arglists ([])})})