Partial function application: Difference between revisions

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(4 16 36 64)</pre>

The <tt>*+2</tt> is also a form of partial application in Perl 6. In this case we partially apply the <tt>infix:<+></tt> function with a second argument of 2. That is, the star (known as the "whatever" star) indicates which argument <em>not</em> to apply. In contrast to languages that keep some arguments unbound by leaving holes, the explicit star in Perl 6 allows us to avoid syntactic ambiguity in whether to expect a term or an infix operator; such self-clocking code contributes to better error messages when things go wrong.

=={{header|Phix}}==

Phix does not explicitly support currying, but you can easily emulate it with routine_id<br>

<lang Phix>function fs(integer rid, sequence s)

for i=1 to length(s) do

s[i] = call_func(rid,{s[i]})

end for

return s

end function

function p_apply(sequence f, sequence args)

return call_func(f[1],{f[2],args})

end function

function f1(integer i)

return i+i

end function

function f2(integer i)

return i*i

end function

constant fsf1 = {routine_id("fs"),routine_id("f1")},

fsf2 = {routine_id("fs"),routine_id("f2")}

?p_apply(fsf1,{0,1,2,3})

?p_apply(fsf2,{2,4,6,8})</lang>

<pre>

{0,2,4,6}

{4,16,36,64}

</pre>

Should you want the first few arguments set as part of fsf1/2 [ie as a 3rd sequence element], then obviously p_apply might be more like

<lang Phix>function p_apply(sequence ffsa, sequence extra_args)

object {fa,fx,set_args} = ffsa

return call_func(fa,{fx,set_args&extra_args})

end function</lang>

=={{header|PicoLisp}}==