Proc#curry doesn't always detect too many arguments
Currently, Proc#curry checks the validity of the
arity argument and will raise an error if:
1) arity is less than the number of required arguments or
2) arity is more than the maximum number of arguments
Note that simple Procs always accept any number of arguments (even though they may be ignored), so (2) doesn't applies to them, only to lambda's and procs made from methods.
#2 isn't done as well as it could in case of limited optional parameters:
def Object.foo(a, b=42); end def Object.bar(a, b); end Object.method(:foo).to_proc.curry(3) # => curried proc which will raise an error only when passed it's 3rd parameter Object.method(:bar).to_proc.curry(3) # => ArgumentError: wrong number of arguments (3 for 2) Same thing with lambdas
My proposed fix passes SST:
a) usefulness: "fail-early" principle [ruby-core:24130]
b) consistency: both methods can only accept a maximum of 2 parameters and are thus treated consistently when attempting to curry with more than 2 arguments
c) intuitiveness and d) performance: similar
It is straightforward (but not obvious), as it passes NIT (but not ODT).