Re: Specializing Functions with Currying

good description of currying - it took me ages to understand this concept (through studies of Scheme, Lisp and Haskell over the years), and it didnt finally twig until I was having to extend some legacy C code here - at one point in the code I knew I would eventually call a key function, but I didn't have all the information in scope right then. I remember thinking 'if only I could have a new function that called that one, using the arguments I have now, and the arguments the new function _will_ have in scope when it gets invoked - I could just pass a function pointer to that new function, instead of chaining all these parameters together and passing long parameter lists around...hey!!'

another good name is 'partial application of functions' - your calling it with a partial list of parameters...

any idea how you would do multiple application of these attributes - e.g. bold _and_ italic

use brain;

Comment on Re: Specializing Functions with Currying

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Re^2: Specializing Functions with Currying by Aristotle (Chancellor) on Aug 06, 2004 at 03:12 UTC
It's not really doable with the simpleminded `curry()` used here. You'll have to construct this manually. `'boldital' => do { my $i = curry \&wrap_with_html => ( 'i' ); my $b = curry \&wrap_with_html => ( 'b' ); sub { $b->( $i->( @_ ) ) } },` [download] Makeshifts last the longest.	[reply] [d/l]
Re^3: Specializing Functions with Currying by FoxtrotUniform (Prior) on Aug 06, 2004 at 03:23 UTC
`'boldital' => do { my $i = curry \&wrap_with_html => ( 'i' ); my $b = curry \&wrap_with_html => ( 'b' ); sub { $b->( $i->( @_ ) ) } },` [download] Neat use of `=>`. As for composition, as an inveterate Haskell hacker (well, hacker-wannabe), I'd prefer to have that as a primitive, too: `sub compose { my ($f, $g) = @_; return sub { $f->($g->(@_)); } } # ... 'boldital' => &compose(&curry(\&wrap_with_html, 'i'), &curry(\&wrap_with_html, 'b')),` [download] The idea of functions that operate on functions and return other functions is much more useful than it first seemed to me. If you never think about functions as first-class objects, having a `compose` function seems incredibly redundant. Once you start building functions on-the-fly, composition becomes indispensible. I guess I should write part 2 of my Perlesque Intro to Haskell, then. `-- F o x t r o t U n i f o r m Found a typo in this node? /msg me % man 3 strfry`	[reply] [d/l] [select]
Re^4: Specializing Functions with Currying by stvn (Monsignor) on Aug 06, 2004 at 13:46 UTC
Why limit `compose` to just two functions? `sub compose { my ($f, $f2, @rest) = @_; return $f unless defined $f2; return &compose(sub { $f2->($f->(@_)) }, @rest); } *bold_italic_and_underlined_paragraph = compose( &curry(\&wrap_with_html, 'u'), &curry(\&wrap_with_html, 'b'), &curry(\&wrap_with_html, 'i'), &curry(\&wrap_with_html, 'p') ); print bold_italic_and_underlined_paragraph("test");` [download] -stvn	[reply] [d/l] [select]
Re^5: Specializing Functions with Currying by Aristotle (Chancellor) on Aug 06, 2004 at 22:55 UTC
Re^5: Specializing Functions with Currying by jryan (Vicar) on Aug 06, 2004 at 21:03 UTC
Re^6: Specializing Functions with Currying by stvn (Monsignor) on Aug 06, 2004 at 21:56 UTC
Some notes below your chosen depth have not been shown here
Re^4: Specializing Functions with Currying by Aristotle (Chancellor) on Aug 06, 2004 at 04:38 UTC
I had seen that some primitive exists for this kind of thing in functional programming, but I have never gotten past a brief foray into that world. My first contact with a number of functional concepts was through Perl, and ever since I've meant to learn a serious functional language. It hasn't happened yet… For anyone looking for an introduction to functional concepts in Perl, Mark-Jason Dominus' Higher Order Perl book is well worth a look… or will be once it's finished. Makeshifts last the longest.	[reply]
Re^3: Specializing Functions with Currying by thor (Priest) on Aug 09, 2004 at 15:03 UTC
It's not really doable with the simpleminded curry() used here. Perhaps I'm missing something, but what if you did this: `my %handler = ( "bold_italic" = curry(\&wrap_with_html,"b><i"), );` [download] thor Feel the white light, the light within Be your own disciple, fan the sparks of will With all of us waiting, your kingdom will come	[reply] [d/l]
Re^4: Specializing Functions with Currying by Aristotle (Chancellor) on Aug 09, 2004 at 15:38 UTC
Err, yes, but that wasn't the point. It's a funny hack, but a hack. `:-)` It doesn't apply to the general case where one wants to compose functions. Makeshifts last the longest.	[reply]
Re^4: Specializing Functions with Currying by miro (Friar) on Aug 10, 2004 at 07:05 UTC
The closing tag would be incorrect if you just add a slash before the string.	[reply]
Re^5: Specializing Functions with Currying by thor (Priest) on Aug 10, 2004 at 11:54 UTC


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