Posted Dec 19, 2011 20:14 UTC (Mon) by HelloWorld
In reply to: turing complete
Parent article: Cracks in the Foundation (PHP Advent)
It's not nonsense, of course you can write web sites with the untyped lambda calculus.
No you can't.
The input to your web-site function is a number representing an HTTP request and a magic cookie value, and the result of the function is a number representing the new magic cookie value and the HTTP result. See?
Yes, I indeed see you didn't get the point.
In PHP, the APIs for accessing the HTTP request data and for setting HTTP response headers and sending data are part of the language; in the untyped lambda calculus, they aren't. Of course, you can alter the language specification of the untyped lambda calculus to include side effects by specifying that your program will be passed an HTTP request and its output will be sent to the client. But if you alter the language that way, it's not the untyped lambda calculus any longer.
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