From: "Eregon (Benoit Daloze)" Date: 2022-03-18T13:14:44+00:00 Subject: [ruby-core:107976] [Ruby master Feature#18644] Coerce anything callable to a Proc Issue #18644 has been updated by Eregon (Benoit Daloze). As background, `to_proc` already exists as a coercion protocol, it's what is used for `call(&callable)`, and there is already `Proc#to_proc`. I think Option 1 makes sense and would be good to add, since indeed we can easily produce a Proc from a call-able object via `method(:call).to_proc` as shown (there is also `-> (*a, **kw) { call(*a, **kw) }`, but that loses arity & parameters information). Option 2 is IMHO less good, because it wouldn't help for `call(&callable)` and doesn't simply use the existing protocol. ---------------------------------------- Feature #18644: Coerce anything callable to a Proc https://bugs.ruby-lang.org/issues/18644#change-96926 * Author: waiting_for_dev (Marc Busqu��) * Status: Open * Priority: Normal ---------------------------------------- Functional objects are increasingly popular in Ruby. Having objects that respond to `#call` makes them interchangeable with a `Proc`. However, when you need to perform some Proc-specific operation, like currying, you have to break the abstraction and ask for the type of object. Example: ```ruby (callable.is_a?(Proc) ? callable : callable.method(:call)).curry[value] ``` Because of https://bugs.ruby-lang.org/issues/18620, it's not possible to make them polymorphic by taking the `:call` method: ```ruby callable.method(:call).curry[value] # won't work! ``` Consequently, I propose adding a built-in Ruby way to coerce anything callable to a proc (examples in Ruby): ### Option 1: `Object#to_proc` ```ruby class Object def to_proc return method(:call).to_proc if respond_to?(:call) raise "Needs to respond to :call" end end class Proc def to_proc self end end callable.to_proc.curry[value] ``` ### Option 2. `Kernel#Proc` ```ruby class Kernel def Proc(value) if value.is_a?(::Proc) value elsif value.respond_to?(:call) value.method(:call).to_proc else raise "Needs to implement :call" end end end Proc(callable).curry[value] ``` -- https://bugs.ruby-lang.org/ Unsubscribe: