Getting at list items

[cpb]

what’s the best way to get the last item in a list?
tried last but Luna doesn’t seem to use it…

[marcin.kostrzewa]

Oh, that’s an accidental omission. I’ll add that to the next release.
For now, you can use myList.reverse.head, to get Maybe the last element (that is safe even if the list was empty). If you are sure the list was non-empty, just use myList.reverse.head.get (get takes a Maybe a and returns the a if it was Just, or throws an error otherwise).

[cpb]

got it thanks,
also it returns maybe time regardless of .get

import Std.Time
«7»
«26»def getfirstorlastwd tt wd fol:
    «51»eom = tt.endOfMonth
    «63»dd = (eom . format "%d") . toInt 
    «53»mm = (eom . format "%m") . toInt
    «54»yy = (eom . format "%y") . toInt 
    «55»wds = 1 . upto dd . each (x: «56»(Time.fromTimeOfYear yy mm x Nothing))
    «57»wt = wds . filter(x«59»: «59»x . format "%a" == wd)
    «60»o = if fol == 0 then wt.head else wt.reverse.head
    «58»o
«49»
«9»def main:
    «61»tn = Time.now
    «37»wd = getfirstorlastwd tn "Wed" 0
    «62»isold = if tn >= wd then 1 else 0
    None
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[marcin.kostrzewa]

head always returns Maybe. If you modify o inside getfirstorlastwd to

o = if fol == 0 then wt.head.get else wt.reverse.head.get

it works. You can also write

o = (if fol == 0 then wt else wt.reverse).head.get

to refactor out the .head.get chain. Or just do it when calling in main:

wd = getfirstorlastwd tn "Wed" 0 . get

I’ve tried all of these combinations and they work fine.

There is, however yet another omission I have just realized when trying out your code – the >= operator will not work for times. I’ll fix this ASAP (together with adding last on list), but for now, you’ll have to write

isold = if (tn == wd).or (tn > wd) then 1 else 0

Sorry for this, I don’t know how did this one slip through.