[Haskell] NYTimes.com: John W. Backus, 82, Fortran Developer, Dies

Dan Weston westondan at imageworks.com
Tue Mar 20 16:00:18 EDT 2007

Douglas Philips wrote:
> On 2007 Mar 20, at 3:30 PM, Dan Weston indited:
>> I looked up John Backus on wikipedia and followed a link to ALGOL:
>> http://en.wikipedia.org/wiki/ALGOL_60
>> where the following "undesirable" property of call-by-name is mentioned.
>> "ALGOL 60 allowed for two evaluation strategies for parameter passing: 
>> the common call-by-value, and call-by-name. Call-by-name had certain 
>> limitations in contrast to call-by-reference, making it an undesirable 
>> feature in language design. For example, it is impossible in ALGOL 60 
>> to develop a procedure that will swap the values of two parameters if 
>> the actual parameters that are passed in are an integer variable and 
>> an array that is indexed by that same integer variable. However, 
>> call-by-name is still beloved of ALGOL implementors for the 
>> interesting thunks that are used to implement it."
>> I suppose that call-by-name is still beloved of Haskell implementors 
>> as well?
> Notice that the "problem" with call-by-name is when side-effects are 
> involved. In a pure-functional-environment those "problems" don't arise...
>             --Doug

It was the phrase "making it an undesirable feature in language design"
  that jumped out at me. Here "language" is an implicitly universally 
quantified variable, and the phrase beta-reduces to "call-by-name is an 
undesirable feature in Haskell design".

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