Function types are like exponentiation for cardinality¶

The cardinality of a function type is the second argument to the power of the first.

$f: a \rightarrow b$

$|f| = |b|^{|a|}$

$g: \text{Boolean} \rightarrow \text{Boolean}$

$|g| = |\text{Boolean}|^{|\text{Boolean}|} = 4$

References¶