given a list of variables

variables = {a, b, c};

I want to automatically define a function

f[{a_,b_,c_},x_] := g[a,b,c,x]

(I do need a delayed assignment here, since g is a compiled function).

As a first attempt I define

f[Evaluate[Pattern[#,Blank[]]&/@variables], x_] := Evaluate[Append[variables, x]]

which works out as



This is good so far.

As a next step I want to pass the parameter list to the function g:

f[Evaluate[Pattern[#,Blank[]]&/@variables], x_] := g @@ Evaluate[Append[variables, x]]

This does not work, as the argument list for g is now left unevaluated:



What do I need to change in my definition of f in order to get



Thanks for any help! Roman

  • 1
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    – bbgodfrey
    Commented Feb 24, 2015 at 16:38
  • $\begingroup$ something like f[p : Pattern @@@ Thread[{variables, _}], x_] := g[## & @@ p, x]? $\endgroup$
    – kglr
    Commented Feb 24, 2015 at 16:43
  • $\begingroup$ Bill, as g is a compiled function, I cannot evaluate the whole RHS. $\endgroup$
    – Roman
    Commented Feb 24, 2015 at 16:50

2 Answers 2


I think this approach is an overreaction. Maybe something like this will be ok?

f[l_, x_] := g[##, x] & @@ l
  • $\begingroup$ Kuba, yes, much simpler! Thanks a lot. $\endgroup$
    – Roman
    Commented Feb 24, 2015 at 16:59
  • $\begingroup$ kguler, naming the pattern is a good idea. But in this case I think Kuba's solution is simpler, by avoiding naming of the individual components of the parameter list at all. $\endgroup$
    – Roman
    Commented Feb 24, 2015 at 17:00

While Kuba's answer is simpler, what you asked for can be accomplished also rather easily with the help of the nested injector pattern:

variables /. {vars__} :> 
    (Map[Pattern[#, Blank[]] &, {vars}] /. {patts__} :>  
         (f[{patts}, x_] := g[vars, x]))

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