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|
datatype 'a parList =
NIL
| CONS of 'a * index
fun listInitialize cell L =
case L of
nil => cell NIL
| h :: tail =>
let
val tailIndex = listInitialize cell tail
in
cell (CONS(h, tailIndex))
end
fun listInitialize (K: index -> index) cell L =
case L of
nil => K (cell NIL)
| h :: tail =>
let
val newK = fn i => K (cell (CONS(h, i)))
in
listInitialize newK cell tail
end
fun listFinalize value =
let
fun conv i =
case value i of
NIL => nil
| CONS(head, tail) => head :: conv tail
in
conv
end
val whereParam =
{size = fn L => List.length L + 1,
initialize = fn x => listInitialize (fn (x:index) => x) x,
default = NIL,
finalize = listFinalize}
fun mapList f L =
_foreach id in L where whereParam
with {value, newValue, size}
do case value id of
NIL => NIL
| CONS(head, tail) => CONS(f head, tail)
while false
end
|
