Literal pattern
A literal pattern consists of a single specific value. For example,
f(5) = "hi"
uses 5 as a literal pattern, and means that on the specific input
5, the function f should output "hi".
Literal patterns can be used with
The unit value, e.g.
f(unit) = ...Booleans, e.g.
f(true) = ...Natural numbers, e.g.
f(5) = ...Integers, e.g.
f(-5) = ...Rational numbers, e.g.
f(1/2) = ...Characters, e.g.
f('x') = ...Strings, e.g.
f("hello") = ...
Note that f(-5) = ... and f(1/2) = ... are technically
arithmetic patterns rather than true literal
patterns, but the distinction does not matter very much.