Feature #9783
closed[PATCH] Add Method#curry
Description
There is already Proc#curry, but to curry a method you need to go through to_proc. This patch adds Method#curry
which delegates to method.to_proc.curry
.
Looking forward to seeing this discussed.
Files
Updated by plexus (Arne Brasseur) over 10 years ago
- File 0001-Implement-Method-curry-which-delegates-to-to_proc.cu.patch 0001-Implement-Method-curry-which-delegates-to-to_proc.cu.patch added
Updated the patch with documentation. There's an interesting side effect to be considered. Method#to_proc
returns a lambda that checks its arity. Proc#curry
takes an optional arity
argument. If this doesn't match the method's arity then the result can not be called.
def two_args(a,b)
end
curried = method(:two_args).to_proc.curry(1)
curried.(1)
# -:4:in `curry': wrong number of arguments (1 for 2) (ArgumentError)
# from -:4:in `<main>'
curried.(1, 2)
# -:4:in `curry': wrong number of arguments (1 for 2) (ArgumentError)
# from -:4:in `<main>'
curried.(1, 2, 3)
# -:4:in `curry': wrong number of arguments (1 for 2) (ArgumentError)
# from -:4:in `<main>'
In the case of a method with variable arguments the arity argument is important though, because otherwise the currying has no effect.
def varargs(*args)
args
end
curried = method(:varargs).to_proc.curry
curried.(1) # => [1]
curried.(1,2) # => [1, 2]
curried = method(:varargs).to_proc.curry(3)
curried.(1) # => #<Proc:0x007f0cb8fc6fe0 (lambda)>
curried.(1).(2).(3) # => [1, 2, 3]
I think it would make sense for a Method#curry
method to raise an error or at least give a warning when passing the wrong arity to a fixed-arity function.
Updated by matz (Yukihiro Matsumoto) over 10 years ago
Looks good to me, except that I don't see any real use-case.
But it's true for Proc#curry itself.
Matz.
Updated by nobu (Nobuyoshi Nakada) over 10 years ago
- Status changed from Open to Closed
- % Done changed from 0 to 100
Applied in changeset r46461.
proc.c: Implement Method#curry
- proc.c (rb_method_curry): Implement Method#curry, which delegates
to to_proc.curry. [ruby-core:62212] [Feature #9783]