`be` is not stack safe

[paulyoung]

I'm seeing RangeError: Maximum call stack size exceeded inside of this function.

purescript-prettier-printer/src/Prettier/Printer.purs

Lines 102 to 111 in 32fbcea

	be :: Int -> Int -> List (Tuple Int DOC) -> Doc
	be w k List.Nil = Nil
	be w k (Cons (Tuple i NIL) z) = be w k z
	be w k (Cons (Tuple i (APPEND x y)) z) = be w k $ (Tuple i x) : (Tuple i y) : z
	be w k (Cons (Tuple i (NEST j x)) z) = be w k $ (Tuple (i + j) x) : z
	be w k (Cons (Tuple i (TEXT s)) z) = Text s $ be w (k + String.length s) z
	be w k (Cons (Tuple i LINE) z) = Line i $ be w i z
	be w k (Cons (Tuple i (UNION x y)) z) =
	let x' = be w k $ (Tuple i x) : z
	in if fits (w - k) x' then x' else be w k $ (Tuple i y) : z

It's not exported so hopefully this can be addressed without any breaking changes.

[paulyoung]

Compiled JS, FWIW.

var be = function (w) {
    return function (k) {
        return function (v) {
            if (v instanceof Data_List_Types.Nil) {
                return Nil.value;
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof NIL) {
                return be(w)(k)(v.value1);
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof APPEND) {
                return be(w)(k)(new Data_List_Types.Cons(new Data_Tuple.Tuple(v.value0.value0, v.value0.value1.value0), new Data_List_Types.Cons(new Data_Tuple.Tuple(v.value0.value0, v.value0.value1.value1), v.value1)));
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof NEST) {
                return be(w)(k)(new Data_List_Types.Cons(new Data_Tuple.Tuple(v.value0.value0 + v.value0.value1.value0 | 0, v.value0.value1.value1), v.value1));
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof TEXT) {
                return Text.create(v.value0.value1.value0)(be(w)(k + Data_String.length(v.value0.value1.value0) | 0)(v.value1));
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof LINE) {
                return Line.create(v.value0.value0)(be(w)(v.value0.value0)(v.value1));
            };
            if (v instanceof Data_List_Types.Cons && v.value0.value1 instanceof UNION) {
                var x$prime = be(w)(k)(new Data_List_Types.Cons(new Data_Tuple.Tuple(v.value0.value0, v.value0.value1.value0), v.value1));
                var $102 = fits(w - k | 0)(x$prime);
                if ($102) {
                    return x$prime;
                };
                return be(w)(k)(new Data_List_Types.Cons(new Data_Tuple.Tuple(v.value0.value0, v.value0.value1.value1), v.value1));
            };
            throw new Error("Failed pattern match at Prettier.Printer line 102, column 1 - line 102, column 48: " + [ w.constructor.name, k.constructor.name, v.constructor.name ]);
        };
    };
};