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Add foldl' primop

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This commit is contained in:
Eelco Dolstra 2015-07-23 17:03:02 +02:00
parent 887bb5fa5a
commit 61af14a921
3 changed files with 38 additions and 1 deletions
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24
src/libexpr/primops.cc
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@ -1304,6 +1304,29 @@ static void prim_length(EvalState & state, const Pos & pos, Value * * args, Valu
}
/* Reduce a list by applying a binary operator, from left to
right. The operator is applied strictly. */
static void prim_foldlStrict(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
state.forceFunction(*args[0], pos);
state.forceList(*args[2], pos);
Value * vCur = args[1];
if (args[2]->list.length)
for (unsigned int n = 0; n < args[2]->list.length; ++n) {
Value vTmp;
state.callFunction(*args[0], *vCur, vTmp, pos);
vCur = n == args[2]->list.length - 1 ? &v : state.allocValue();
state.callFunction(vTmp, *args[2]->list.elems[n], *vCur, pos);
}
else
v = *vCur;
state.forceValue(v);
}
/*************************************************************
* Integer arithmetic
*************************************************************/
@ -1641,6 +1664,7 @@ void EvalState::createBaseEnv()
addPrimOp("__elem", 2, prim_elem);
addPrimOp("__concatLists", 1, prim_concatLists);
addPrimOp("__length", 1, prim_length);
addPrimOp("__foldl'", 3, prim_foldlStrict);
// Integer arithmetic
addPrimOp("__add", 2, prim_add);