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Re: Partial Function Application -- Advantages over normal function?

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  Re: Partial Function Application -- Advantages over normal function? Dave Angel <davea@ieee.org> - 2011-07-18 17:45 -0400
    Re: Partial Function Application -- Advantages over normal function? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-07-19 00:28 +0200
      Re: Partial Function Application -- Advantages over normal function? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-07-19 00:33 +0200
        Re: Partial Function Application -- Advantages over normal function? Thomas Jollans <t@jollybox.de> - 2011-07-19 08:22 +0200
        Re: Partial Function Application -- Advantages over normal function? Ian Kelly <ian.g.kelly@gmail.com> - 2011-07-19 10:49 -0600
        Re: Partial Function Application -- Advantages over normal function? Thomas Jollans <t@jollybox.de> - 2011-07-19 18:58 +0200
        Re: Partial Function Application -- Advantages over normal function? Ian Kelly <ian.g.kelly@gmail.com> - 2011-07-19 11:15 -0600
      Re: Re: Partial Function Application -- Advantages over normal function? Dave Angel <davea@ieee.org> - 2011-07-19 06:07 -0400
      Re: Partial Function Application -- Advantages over normal function? Terry Reedy <tjreedy@udel.edu> - 2011-07-19 12:47 -0400

#9836 — Re: Partial Function Application -- Advantages over normal function?

On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
> On 7/18/2011 8:24 AM, Paul Woolcock wrote:
>> Partial function application (or "currying") is the act of taking a
>> function with two or more parameters, and applying some of the arguments
>> in order to make a new function.  The "hello world" example for this
>> seems to be this:
>> <snip>
>
> def makeadder(y)
>     def _add(x): return x+y
> add2 = makeadder(2)
>
> <snip>

A couple of typos in that code:


def makeaddr(y):
     def _add(x): return x+y
     return _add


DaveA

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#9838

Dave Angel wrote:

> On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
>> def makeadder(y)
>>     def _add(x): return x+y
>> add2 = makeadder(2)
> 
> A couple of typos in that code:
> 
> 
> def makeaddr(y):
>      def _add(x): return x+y
>      return _add

I agree about the `return' statement, but not about the factory name; this 
has nothing to do with addresses (addr).

-- 
PointedEars

Bitte keine Kopien per E-Mail. / Please do not Cc: me.

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#9839

Thomas 'PointedEars' Lahn wrote:

> Dave Angel wrote:
>> On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
>>> def makeadder(y)
>>>     def _add(x): return x+y
>>> add2 = makeadder(2)
>> 
>> A couple of typos in that code:
>> 
>> def makeaddr(y):
>>      def _add(x): return x+y
>>      return _add
> 
> I agree about the `return' statement, but not about the factory name; this
> has nothing to do with addresses (addr).

Supplemental: The above can be simplified to

def makeadder(y): return lambda x: x + y

-- 
PointedEars

Bitte keine Kopien per E-Mail. / Please do not Cc: me.

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#9858

On 19/07/11 00:33, Thomas 'PointedEars' Lahn wrote:
> Thomas 'PointedEars' Lahn wrote:
> 
>> Dave Angel wrote:
>>> On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
>>>> def makeadder(y)
>>>>     def _add(x): return x+y
>>>> add2 = makeadder(2)
>>>
>>> A couple of typos in that code:
>>>
>>> def makeaddr(y):
>>>      def _add(x): return x+y
>>>      return _add
>>
>> I agree about the `return' statement, but not about the factory name; this
>> has nothing to do with addresses (addr).
> 
> Supplemental: The above can be simplified to
> 
> def makeadder(y): return lambda x: x + y
> 

In turn:

makeadder = lambda y: lambda x: x + y

Smells of Haskell.

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#9889

On Tue, Jul 19, 2011 at 12:22 AM, Thomas Jollans <t@jollybox.de> wrote:
>> Supplemental: The above can be simplified to
>>
>> def makeadder(y): return lambda x: x + y
>>
>
> In turn:
>
> makeadder = lambda y: lambda x: x + y

That's not an improvement.  lambda is for making anonymous functions.
If you're going to construct a lambda and bind it to a name, you
should just use def.

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#9890

On 19/07/11 18:49, Ian Kelly wrote:
> On Tue, Jul 19, 2011 at 12:22 AM, Thomas Jollans <t@jollybox.de> wrote:
>>> Supplemental: The above can be simplified to
>>>
>>> def makeadder(y): return lambda x: x + y
>>>
>>
>> In turn:
>>
>> makeadder = lambda y: lambda x: x + y
> 
> That's not an improvement.  lambda is for making anonymous functions.
> If you're going to construct a lambda and bind it to a name, you
> should just use def.

No, it's not an improvement. It's an illustration.

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#9896

On Tue, Jul 19, 2011 at 10:58 AM, Thomas Jollans <t@jollybox.de> wrote:
> No, it's not an improvement. It's an illustration.

I get that.  The difference I pointed out between your
"simplification" and the other Thomas's is the reason why yours would
be unpythonic whilst his is fine.

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#9870

On 01/-10/-28163 02:59 PM, Thomas 'PointedEars' Lahn wrote:
> Dave Angel wrote:
>
>> On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
>>> def makeadder(y)
>>>      def _add(x): return x+y
>>> add2 = makeadder(2)
>> A couple of typos in that code:
>>
>>
>> def makeaddr(y):
>>       def _add(x): return x+y
>>       return _add
> I agree about the `return' statement, but not about the factory name; this
> has nothing to do with addresses (addr).
>

The two changes that I made deliberately were adding the colon and 
adding the return statement.  I'm not sure how the name got changed;  
that was accidental.

DaveA

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#9888

On 7/19/2011 6:07 AM, Dave Angel wrote:
> On 01/-10/-28163 02:59 PM, Thomas 'PointedEars' Lahn wrote:
>> Dave Angel wrote:
>>
>>> On 01/-10/-28163 02:59 PM, Terry Reedy wrote:
>>>> def makeadder(y)
>>>> def _add(x): return x+y
>>>> add2 = makeadder(2)
>>> A couple of typos in that code:
>>>
>>>
>>> def makeaddr(y):
>>> def _add(x): return x+y
>>> return _add
>> I agree about the `return' statement, but not about the factory name;
>> this
>> has nothing to do with addresses (addr).
>>
>
> The two changes that I made deliberately were adding the colon and
> adding the return statement. I'm not sure how the name got changed; that
> was accidental.

Anyway, my apologies for posting quickly without testing and without 
saying so. I know better and too often leave in mistakes when I do.

-- 
Terry Jan Reedy

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