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1 point by rntz 5658 days ago | link | parent

That'll work fine, although the 'do in your function is unnecessary. Also, there is a macro 'or= that does precisely what your first line does (assigns a value to a place if it is nil):

    (def filltbl (tbl keys vals)
      (or= tbl (table))
      (map (fn (k v) (= tbl.k v)) keys vals))


1 point by thaddeus 5658 days ago | link

I'm not sure how any of these can work for intializing a table that's not aleady a table...

  (= k* '("1" "2" "3"))
  (= v* '("One" "Two" "Three"))

  assuming t* has not been set - this is what I get: 

  arc> (filltbl t* k* v*)
  Error: "reference to undefined identifier: _t*"
  
  or even:

  arc> (filltbl 't* k* v*)
  Error: "Can't set reference  t* \"1\" \"One\""

  so what am I missing ?

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2 points by rntz 5658 days ago | link

filltbl isn't a macro, nor does it affect the global namespace. As written, it just creates a table if its first arg is nil. Of course, this is useless unless it returns that table... oops.

    (def filltbl (tbl keys vals)
      (or= tbl (table))
      (map (fn (k v) (= tbl.k v)) keys vals)
      tbl)
IMO, a more idiomatic way to represent this would be to use optional arguments, although that requires altering the argument order:

    (def filltbl (keys vals (o tbl (table)))
      (map (fn (k v) (= tbl.k v)) keys vals))
      tbl)

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1 point by thaddeus 5658 days ago | link

yeah I tried passing nil in, and got nothing back, so I figured it was supposed to create the table - I should have seen that too.

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1 point by adm 5657 days ago | link

Can this be part of arc.arc?

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1 point by shader 5657 days ago | link

You could push it onto Anarki. Other than that, there isn't much you can do to get it into a public arc.arc. It seems that if a function isn't used in the forum code, pg doesn't include it in the official release.

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