       Re: List to Expression

• To: mathgroup at smc.vnet.net
• Subject: [mg106088] Re: [mg106055] List to Expression
• From: Adriano Pascoletti <adriano.pascoletti at dimi.uniud.it>
• Date: Fri, 1 Jan 2010 05:34:29 -0500 (EST)
• References: <200912310817.DAA24881@smc.vnet.net>

```A solution using ReplaceAll (/.):

In:= l = {a, {b, {c, d}}}; l /. {x_, y_} :> x[y]
% /. {x_, y_} :> x[y]
% /. List -> Sequence
Out= a[{b, {c, d}}]
Out= a[b[{c, d}]]
Out= a[b[c, d]]

In:= l /. {x_, y_} :> x[y] /. {x_, y_} :> x[y] /. List -> Sequence
Out= a[b[c, d]]

2009/12/31 Spell <l_sharonj at hotmail.com>

> 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
>  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.
>
>

```

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