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Re: List to Expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106078] Re: [mg106055] List to Expression
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Fri, 1 Jan 2010 05:32:36 -0500 (EST)
  • References: <200912310817.DAA24881@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

Close, but no cigar:

{a, {b, {c, d}}} /. List -> Compose

a[b[c[d]]]

ditto:

expr = {a, {b, {c, d}}};
k = Depth@expr;
Replace[expr, List -> Compose, {0, k - 2}, Heads -> True]

Perfect:

expr //. {{a_, b_List} :> a[b], List -> Sequence}

a[b[c, d]]

Bobby

On Thu, 31 Dec 2009 02:17:33 -0600, Spell <l_sharonj at hotmail.com> wrote:

> Hellp,
>
> I am having trouble converting a list into an "expression". For example  
> suppose I have the following list expression.
>    l = {a, {b, {c, d}}}
>
> When I evaluate the FullForm version, I get an output with List as the  
> Head.
>  List[a,List[b,List[c,d]]]
>
> But, I would like the following output instead: a[b[c,d]], wondering how  
> this would be accomplised.
>
> PS:
> Essentially, I have a FunctionSet with various functions in it. And  
> would like to generate a tree of functions, from the FunctionSet. So,  
> say I have functions from a to d in the set. Then, I can generate  
> something like: d[a[b], c[d[a[b]]].
>
> Thank you.
>


-- 
DrMajorBob at yahoo.com


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