It’s a bit of an edge case. Map[f, expr]
applies f
to each element of expression at level 1. Note that it works with any expression, not just lists:
In[12]:= Map[g, f[1,2,3]]
Out[12]= f[g[1],g[2],g[3]]
Since x
is a symbol, it doesn’t have any parts. Compare to
In[13]:= Map[f,g[]]
Out[13]= g[]