Function if
From ftm
Contents |
[edit]
Syntax
if <num: condition> <any: true value> [<any: false value>]
[edit]
Synopsis:
Choose between two values (both conditional values are evaluated). If the <false value> argument is missing, nothing is output.
[edit]
Description
The if function (not method) should be pretty clear if you keep in mind the two drawbacks:
1. it is a function, i.e. all three arguments are evaluated before the if gets to decide which one to output, i.e. something like
(if ($1 != 1) ($myfmat mul 2) ($myfmat zero))
always multiplies and then zeros the myfmat!
2. The result of if can only be one atom, not a list. If you want to output one list or another, use tuples, with a subsequent ftm.list, the list function, or the output tuples as list (untuple) inspector option of ftm.mess. This can be used with a 'route' to send different lists out to one or another connection, like this:
(if ($mydict exists $1) {1 $mydict[$1]} {2 $1 42})
|
ftm.list
|
route 1 2
or
(list (if ($mydict exists $1) {1 $mydict[$1]} {2 $1 42}))
|
route 1 2
or with untuple
(if ($mydict exists $1) {1 $mydict[$1]} {2 $1 42})
|
route 1 2
[edit]