op_arity

Type.op_arity : {Thy:string, Tyop:string} -> int option

Return the arity of a type operator.

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

See also

Type.decls