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Contents
#--
# Thanks dave!
#++
class Proc
# Returns a new proc that is the functional
# compostion of two procs, in order.
#
# a = lambda { |x| x + 4 }
# b = lambda { |y| y / 2 }
#
# a.compose(b).call(4) #=> 6
# b.compase(a).call(4) #=> 4
#
def compose(other)
raise ArgumentError, "arity count mismatch" unless arity == other.arity
#proc{ |*a| self.call(other.call(*a)) }
proc{ |*a| self.call(*other.call(*a)) }
end
# Operator for compose.
#
# a = lambda { |x| x + 4 }
# b = lambda { |y| y / 2 }
#
# (a * b).call(4) #=> 6
# (b * a).call(4) #=> 4
#
alias_method( :*, :compose )
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCProc < Test::Unit::TestCase
def test_compose
a = lambda { |x| x + 4 }
b = lambda { |y| y / 2 }
assert_equal( 6, (a.compose(b)).call(4) )
assert_equal( 4, (b.compose(a)).call(4) )
end
def test_compose_op
a = lambda { |x| x + 4 }
b = lambda { |y| y / 2 }
assert_equal( 6, (a * b).call(4) )
assert_equal( 4, (b * a).call(4) )
end
end
=end
Version data entries
16 entries across 16 versions & 1 rubygems