Someone over on the Icon newsgroup asked (indirectly) about
implementing 'anonymous functions' in Icon. I thought folks
here might like to see one approach that works in both Icon
and Unicon.
Sample source code is attached.
--
Steve Wampler -- [EMAIL PROTECTED]
The gods that smiled on your birth are now laughing out loud.
#<p>
# A short demonstration on one way to implement <i>anonymous functions</i>
# in Icon or Unicon using co-expressions. The approach is based on the
# technique used to implement closures described in <b>The Generator</b>
# Vol 2, No 2 [http://unicon.org/generator].
#</p>
procedure main(args)
local C, inVal, outVal
# The anonymous 'function', as a co-expression. Most of the code
# is standard boilerplate needed to use a co-expression as
# an anonymous function.
C := makeProc {
repeat {
inVal := outVal@&source
outVal := inVal[1] + inVal[2] # f(a,b) -> a+b
}
}
# Example invocations
write(invoke(C, 1,2))
write(invoke(C, 3,4))
end
#<p>
# Invokes co-expression <tt>c1</tt> with <tt>a1</tt> as the argument list
#</p>
procedure invoke(c1, a1[])
return [EMAIL PROTECTED]
end
#<p>
# PDCO to preactivate a co-expression so it is ready to accept
# an input value on the next activation.
#</p>
procedure makeProc(A)
return (@A[1],A[1])
end
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