op_arity : {Thy:string, Tyop:string} -> int option
STRUCTURE
SYNOPSIS
Return the arity of a type operator.
DESCRIPTION
An invocation op_arity{Tyop,Thy} returns NONE if the given record does not identify a type operator in the current type signature. Otherwise, it returns SOME n, where n identifies the number of arguments the specified type operator takes.
FAILURE
Never fails.
EXAMPLE
- op_arity{Tyop="fun", Thy="min"};
> val it = SOME 2 : int option

- op_arity{Tyop="foo", Thy="min"};
> val it = NONE : int option

SEEALSO
HOL  Kananaskis-13