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}</syntaxhighlight>
=={{header|
==={{header|BaCon}}===
BaCon has the concept of delimited strings, which may contain delimited strings within delimited strings etc. Such nested delimited strings must be surrounded by (escaped) double quotes in order to avoid their delimiter messing up operations on higher level delimited strings. However, from functional point of view, a delimited string is the same as a regular list. The special function FLATTEN$ can actually flatten out lists within lists. The last SORT$ in the program below makes sure no empty items remain in the list.
<syntaxhighlight lang="qbasic">OPTION COLLAPSE TRUE
Line 502 ⟶ 503:
PRINT SORT$(lst$, ",")</syntaxhighlight>
{{out}}
<pre>"1",2,"\"3,4\",5","\"\\"\\"\"","\"\\"6\\"\"",7,8,""
==={{header|BASIC256}}===
{{trans|FreeBASIC}}
<syntaxhighlight lang="basic256">sComma = "": sFlatter = ""
Line 523 ⟶ 521:
End</syntaxhighlight>
{{out}}
<pre>Igual que la entrada de FreeBASIC.</pre>
==={{header|Chipmunk Basic}}===
{{works with|Chipmunk Basic|3.6.4}}
{{works with|QBasic}}
<syntaxhighlight lang="qbasic">10 cls
20 sstring$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 for sicount = 1 to len(sstring$)
40 if instr("[] ,",mid$(sstring$,sicount,1)) = 0 then
50 sflatter$ = sflatter$+scomma$+mid$(sstring$,sicount,1)
60 scomma$ = ", "
70 endif
80 next sicount
90 print "[";sflatter$;"]"
100 end</syntaxhighlight>
==={{header|FreeBASIC}}===
{{trans|Gambas}}
<syntaxhighlight lang="freebasic">Dim As String sComma, sString, sFlatter
Dim As Short siCount
sString = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
For siCount = 1 To Len(sString)
If Instr("[] ,", Mid(sString, siCount, 1)) = 0 Then
sFlatter += sComma + Mid(sString, siCount, 1)
sComma = ", "
End If
Next siCount
Print "["; sFlatter; "]"
Sleep</syntaxhighlight>
{{out}}
<pre>[1, 2, 3, 4, 5, 6, 7, 8]</pre>
==={{header|FutureBasic}}===
Definitely old school.
<syntaxhighlight lang="futurebasic">
local fn FlattenList( list as Str255 ) as Str255
long i
Str255 flatStr, commaStr
flatStr = ""
for i = 1 to len$(list)
if ( instr$( 0, "[] ,", mid$( list, i, 1 ) ) === 0 )
flatStr += commaStr + mid$( list, i, 1 )
commaStr = ", "
end if
next
end fn = flatStr
window 1, @"Flatten a list", ( 0, 0, 350, 150 )
print "["; fn FlattenList( "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]" ); "]"
HandleEvents</syntaxhighlight>
{{output}}
<pre>[1, 2, 3, 4, 5, 6, 7, 8]</pre>
Modern and a little outside the box.
<syntaxhighlight lang="futurebasic">
void local fn FlattenAList
CFStringRef listStr = @"[[1], 2, [[3, 4], 5], [[[]]], [[[6]]], 7, 8, []]"
CFArrayRef listArr = fn StringComponentsSeparatedByCharactersInSet( listStr, fn CharacterSetWithCharactersInString( @"\"[ ]," ) )
CFMutableArrayRef mutArr = fn MutableArrayWithArray( listArr )
MutableArrayRemoveObject( mutArr, @"" )
CFStringRef flatStr = fn ArrayComponentsJoinedByString( mutArr, @", " )
printf @"[%@]", flatStr
end fn
fn FlattenAList
HandleEvents
</syntaxhighlight>
{{output}}
<pre>[1, 2, 3, 4, 5, 6, 7, 8]</pre>
==={{header|Gambas}}===
'''[https://gambas-playground.proko.eu/?gist=1c0157ce2b7eab99ba4e784e183ba474 Click this link to run this code]'''
<syntaxhighlight lang="gambas">'Code 'borrowed' from Run BASIC
Public Sub Main()
Dim sComma, sString, sFlatter As String
Dim siCount As Short
sString = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
For siCount = 1 To Len(sString)
If InStr("[] ,", Mid$(sString, siCount, 1)) = 0 Then
sFlatter = sFlatter & sComma & Mid(sString, siCount, 1)
sComma = ","
End If
Next
Print "["; sFlatter; "]"
End</syntaxhighlight>
Output:
<pre>[1,2,3,4,5,6,7,8]</pre>
==={{header|GW-BASIC}}===
{{works with|Chipmunk Basic}}
{{works with|QBasic}}
<syntaxhighlight lang="qbasic">10 CLS
20 SSTRING$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 FOR SICOUNT = 1 TO LEN(SSTRING$)
40 IF INSTR("[] ,",MID$(SSTRING$,SICOUNT,1)) = 0 THEN SFLATTER$ = SFLATTER$+SCOMMA$+MID$(SSTRING$,SICOUNT,1): SCOMMA$ = ", "
50 NEXT SICOUNT
60 PRINT "[";SFLATTER$;"]"
70 END</syntaxhighlight>
==={{header|MSX Basic}}===
{{works with|QBasic}}
{{works with|Chipmunk Basic}}
{{works with|GW-BASIC}}
<syntaxhighlight lang="qbasic">10 CLS
20 S$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 FOR SICOUNT = 1 TO LEN(S$)
40 IF INSTR("[] ,",MID$(S$,SICOUNT,1)) = 0 THEN SFLATTER$ = SFLATTER$+SCOMMA$+MID$(S$,SICOUNT,1): SCOMMA$ = ", "
50 NEXT SICOUNT
60 PRINT "[";SFLATTER$;"]"
70 END</syntaxhighlight>
==={{header|PureBasic}}===
<syntaxhighlight lang="purebasic">Structure RCList
Value.i
List A.RCList()
EndStructure
Procedure Flatten(List A.RCList())
ResetList(A())
While NextElement(A())
With A()
If \Value
Continue
Else
ResetList(\A())
While NextElement(\A())
If \A()\Value: A()\Value=\A()\Value: EndIf
Wend
EndIf
While ListSize(\A()): DeleteElement(\A()): Wend
If Not \Value: DeleteElement(A()): EndIf
EndWith
Wend
EndProcedure</syntaxhighlight>
Set up the MD-List & test the Flattening procedure.
<syntaxhighlight lang="purebasic">;- Set up two lists, one multi dimensional and one 1-D.
NewList A.RCList()
;- Create a deep list
With A()
AddElement(A()): AddElement(\A()): AddElement(\A()): \A()\Value=1
AddElement(A()): A()\Value=2
AddElement(A()): AddElement(\A()): \A()\Value=3
AddElement(\A()): \A()\Value=4
AddElement(A()): AddElement(\A()): \A()\Value=5
AddElement(A()): AddElement(\A()): AddElement(\A()): AddElement(\A())
AddElement(A()): AddElement(\A()): AddElement(\A()): \A()\Value=6
AddElement(A()): A()\Value=7
AddElement(A()): A()\Value=8
AddElement(A()): AddElement(\A()): AddElement(\A())
EndWith
Flatten(A())
;- Present the result
If OpenConsole()
Print("Flatten: [")
ForEach A()
Print(Str(A()\Value))
If ListIndex(A())<(ListSize(A())-1)
Print(", ")
Else
PrintN("]")
EndIf
Next
Print(#CRLF$+"Press ENTER to quit"): Input()
EndIf</syntaxhighlight><pre>Flatten: [1, 2, 4, 5, 6, 7, 8]</pre>
==={{header|QBasic}}===
{{works with|QBasic|1.1}}
{{works with|QuickBasic|4.5}}
<syntaxhighlight lang="qbasic">sString$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
FOR siCount = 1 TO LEN(sString$)
IF INSTR("[] ,", MID$(sString$, siCount, 1)) = 0 THEN
sFlatter$ = sFlatter$ + sComma$ + MID$(sString$, siCount, 1)
sComma$ = ", "
END IF
NEXT siCount
PRINT "["; sFlatter$; "]"
END</syntaxhighlight>
==={{header|Run BASIC}}===
{{incorrect|Run BASIC| The task is not in string translation but in list translation.}}
<syntaxhighlight lang="runbasic">n$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
for i = 1 to len(n$)
if instr("[] ,",mid$(n$,i,1)) = 0 then
flatten$ = flatten$ + c$ + mid$(n$,i,1)
c$ = ","
end if
next i
print "[";flatten$;"]"</syntaxhighlight>
{{out}}
<pre>[1,2,3,4,5,6,7,8]</pre>
==={{header|TI-89 BASIC}}===
There is no nesting of lists or other data structures in TI-89 BASIC, short of using variable names as pointers.
==={{header|True BASIC}}===
<syntaxhighlight lang="qbasic">LET sstring$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
FOR sicount = 1 TO LEN(sstring$)
IF pos("[] ,",(sstring$)[sicount:sicount+1-1]) = 0 THEN
LET sflatter$ = sflatter$ & scomma$ & (sstring$)[sicount:sicount+1-1]
LET scomma$ = ", "
END IF
NEXT sicount
PRINT "["; sflatter$; "]"
END</syntaxhighlight>
==={{header|XBasic}}===
{{works with|Windows XBasic}}
<syntaxhighlight lang="xbasic">PROGRAM "Flatten a list"
DECLARE FUNCTION Entry ()
FUNCTION Entry ()
n$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
FOR i = 1 TO LEN(n$)
IF INSTR("[] ,",MID$(n$,i,1)) = 0 THEN
flatten$ = flatten$ + c$ + MID$(n$,i,1)
c$ = ", "
END IF
NEXT i
PRINT "[";flatten$;"]"
END FUNCTION
END PROGRAM</syntaxhighlight>
{{out}}
<pre>[1, 2, 3, 4, 5, 6, 7, 8]</pre>
==={{header|Yabasic}}===
{{trans|FreeBASIC}}
<syntaxhighlight lang="yabasic">sString$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
For siCount = 1 To Len(sString$)
If Instr("[] ,", Mid$(sString$, siCount, 1)) = 0 Then
sFlatter$ = sFlatter$ + sComma$ + Mid$(sString$, siCount, 1)
sComma$ = ", "
End If
Next siCount
Print "[", sFlatter$, "]"
End</syntaxhighlight>
{{out}}
<pre>Igual que la entrada de FreeBASIC.</pre>
==={{header|ZX Spectrum Basic}}===
{{incorrect|ZX Spectrum Basic| The task is not in string translation but in list translation.}}
<syntaxhighlight lang="zxbasic">10 LET f$="["
20 LET n$="[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 FOR i=2 TO (LEN n$)-1
40 IF n$(i)>"/" AND n$(i)<":" THEN LET f$=f$+n$(i): GO TO 60
50 IF n$(i)="," AND f$(LEN f$)<>"," THEN LET f$=f$+","
60 NEXT i
70 LET f$=f$+"]": PRINT f$</syntaxhighlight>
=={{header|BQN}}==
Line 1,305 ⟶ 1,565:
(t
(append (flatten (car mylist)) (flatten (cdr mylist))))))</syntaxhighlight>
The flatten-tree function was added in Emacs 27.1 or earlier.
<syntaxhighlight lang="lisp">
(flatten-tree mylist)
</syntaxhighlight>
=={{header|Erlang}}==
Line 1,636 ⟶ 1,902:
All of this relies on the list being presented as a flat text, which text is then manipulated directly. If the list was manifested in a data structure of some kind with links and suchlike, then tree-traversal of that structure would be needed to reach the leaf entries.
=={{header|Frink}}==
Line 1,665 ⟶ 1,908:
println[flatten[a]]
</syntaxhighlight>
=={{header|GAP}}==
Line 1,959 ⟶ 2,126:
return
end</syntaxhighlight>
=={{header|Insitux}}==
Insitux has a built-in flatten function.
<syntaxhighlight lang="insitux">
(flatten [[1] 2 [[3 4] 5] [[[]]] [[[6]]] 7 8 []])
</syntaxhighlight>
{{out}}
<pre>
[1 2 3 4 5 6 7 8]
</pre>
=={{header|Ioke}}==
Line 3,008 ⟶ 3,185:
flatten(NonList, T, [NonList|T]).
</syntaxhighlight>
=={{header|Python}}==
===Recursive===
<syntaxhighlight lang="python">>>> def flatten(lst):
return sum( ([x] if not isinstance(x, list) else flatten(x)
Line 3,079 ⟶ 3,197:
===Recursive, generative and working with any type of iterable object===
<syntaxhighlight lang="python">>>> def flatten(itr):
>>> for x in itr:
Line 3,107 ⟶ 3,224:
===Non-recursive===
Function flat is iterative and flattens the list in-place. It follows the Python idiom of returning None when acting in-place:
<syntaxhighlight lang="python">>>> def flat(lst):
Line 3,333 ⟶ 3,449:
We repeatedly apply <tt>raze</tt> until the return value converges to a fixed value.
<syntaxhighlight lang="q">(raze/) ((1); 2; ((3;4); 5); ((())); (((6))); 7; 8; ())</syntaxhighlight>
=={{header|Quackery}}==
Line 3,436 ⟶ 3,537:
>> form blk
== "1 2 test a bb 3 4 99"</syntaxhighlight>
=={{header|Refal}}==
<syntaxhighlight lang="refal">$ENTRY Go {
, ((1) 2 ((3 4) 5) ((())) (((6))) 7 8 ()): e.List
= <Prout e.List ' -> ' <Flatten e.List>>
};
Flatten {
= ;
s.I e.X = s.I <Flatten e.X>;
(e.X) e.Y = <Flatten e.X> <Flatten e.Y>;
};</syntaxhighlight>
{{out}}
<pre>((1 )2 ((3 4 )5 )((()))(((6 )))7 8 ()) -> 1 2 3 4 5 6 7 8</pre>
=={{header|REXX}}==
Line 3,501 ⟶ 3,616:
# => [1, 2, [3, 4], 5, [[]], [[6]], 7, 8]
</syntaxhighlight>
=={{header|Rust}}==
Line 3,988 ⟶ 4,090:
puts [flatten {{1} 2 {{3 4} 5} {{{}}} {{{6}}} 7 8 {}}]
# ===> 1 2 3 4 5 6 7 8</syntaxhighlight>
=={{header|Trith}}==
Line 3,996 ⟶ 4,095:
{{omit from|UNIX Shell}}
=={{header|TXR}}==
Line 4,104 ⟶ 4,192:
End Sub
</syntaxhighlight>
=={{header|V (Vlang)}}==
{{trans|PL/I}}
<syntaxhighlight lang="Zig">
fn main() {
arr := "[[1], 2, [[3, 4], 5], [[[]]], [[[6]]], 7, 8, []]"
println(convert(arr))
}
fn convert(arr string) []int {
mut new_arr := []int{}
for value in arr.replace_each(["[","","]",""]).split_any(", ") {if value !="" {new_arr << value.int()}}
return new_arr
}
</syntaxhighlight>
{{out}}
<pre>
[1, 2, 3, 4, 5, 6, 7, 8]
</pre>
=={{header|Wart}}==
Line 4,140 ⟶ 4,248:
{{libheader|Wren-seq}}
A method already exists for this operation in the above module.
<syntaxhighlight lang="
var a = [[1], 2, [[3, 4], 5], [[[]]], [[[6]]], 7, 8, []]
Line 4,149 ⟶ 4,257:
[1, 2, 3, 4, 5, 6, 7, 8]
</pre>
=={{header|zkl}}==
Line 4,198 ⟶ 4,265:
//-->L(1,2,3,4,5,6,7,8)</syntaxhighlight>
This works by recursively writing the contents of lists to a new list. If a list is recursive or cyclic, it will blow the stack and throw an exception.
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