ucg/std/lists.ucg

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let str_join = module{
sep=" ",
list=NULL,
} => {
let joiner = macro(acc, item) => {
result = select (acc.out == ""), NULL, {
true = acc{
out="@@" % (acc.out,item),
},
false = acc{
out="@@@" % (acc.out, acc.sep, item),
},
},
};
let result = (reduce joiner.result {sep=mod.sep, out=""}, (mod.list)).out;
};
let len = module{
list = NULL,
} => {
let counter = macro(acc, item) => {
result = acc + 1,
};
let result = reduce counter.result 0, (mod.list);
};
let reverse = module{
list = NULL,
} => {
let reducer = macro(acc, item) => {
result = [item] + acc,
};
let result = reduce reducer.result [], (mod.list);
};
let enumerate = module{
start = 0,
step = 1,
list = NULL,
} => {
let reducer = macro(acc, item) => {
result = acc{count = acc.count + acc.step, list=acc.list + [[acc.count, item]]},
};
let acc = {count=mod.start, list=[], step=mod.step};
let enumerated = reduce reducer.result acc, (mod.list);
let result = enumerated.list;
};