Re: [Unicon-group] Proposal for changing the parameter type and default value syntax... (fwd)

[Majorinc, Kazimir]

Call by parameter name is emulated with strings in graphic procedures in 
Icon, with some price in the speed and complexity of the implementation. 
However, call by parameter name (CBPN) seems too similar to old BASIC 
subroutines not to provoke some suspects in its substantiality. For 
example, BASIC code

          x:=a; z:=b; GoSub p

provides some (not all) of the functionality of p(x:=a, z:=b) with nearly 
equally elegant syntax, at least in Chaitin's meaning (see for example 
http://www.flownet.com/gat/chaitin.html .) In Unicon, if procedure is 
declared with

          procedure p(l,m,n,x,y,z)

equivalent of the p(x:=a; z:=b) seems to be expression

         (every (l|m|n|x|y|z):=&null) & x:=a & z:=b & p(l,m,n,x,y,z).

The first and the last of the conjuncts are fixed, used always in the same 
form, so even limited Unicon macros allow further simplification. One of 
the possibilities is

         P(x:=a & z:=b)Pend  .

Hence, those who like (or tolerate) macros can manage CBPN for themselves, 
perhaps not in the prettiest possible form, however, it is possible.



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Kazimir Majorinc, Zagreb, Croatia