Bill Allombert on Tue, 30 Oct 2007 12:44:47 +0100 |
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Re: Functions as first-class objects |
On Thu, Oct 11, 2007 at 01:55:16AM +0200, Bill Allombert wrote: > Hello PARI-dev, > > I would like to discuss moving user functions to first-class objects, > and add support for anonymous functions and closures. I have commited an improved version of that patch. The patch adds the following syntax: * (x1,...,xn)->EXPR : create an anonymous function. * x1->EXPR is accepted as a short-hand for (x1)->EXPR * f(x1,...,xn)=EXPR is accepted as a short-hand for f=(x1,...,xn)->EXPR * EXPR(x1,...,xn) evaluate the expression EXPR. If the result is a function, it calls it on (x1,...,xn), else it fails. Incompatibilities: * Calling a function without () no more evaluate it: ? f %2 = (x) -> x^4+1 * f(x)=x^4+1 is equivalent to f=(x)->x^4+1 which return the 'value' (x)->x^4+1 instead of void: ? f(x)=x^4+1 %1 = (x) -> x^4+1 Deficiencies: * It is not possible to define recursive anonymous functions (short of the Y combinator). Maybe we need to add a 'self' construction. Cheers, Bill.