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

SYNOPSIS
Return the arity of a type operator.

KEYWORDS
signature, type operator.

DESCRIBE
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
Type.decls.

----------------------------------------------------------------------