-- Regression guard for the Lua 5.1 FFI of Effect (control flow).

--

-- #78 forE lo hi f iterates over the half-open range [lo, hi) — lo inclusive,

-- hi EXCLUSIVE (per Effect.purs and the JS `for (i = lo; i < hi; i++)`). Lua's

-- numeric `for i = lo, hi` is inclusive of the upper bound, so the naive port

-- ran one extra iteration and never produced an empty range. The fix uses

-- `for i = lo, hi - 1`.

--

-- `Effect a` here is a zero-arg thunk; `f :: Int -> Effect Unit` is a curried

-- `function(i) return function() ... end end`.

-- Run from the repo root: `lua test/regression/effect.lua`.

local E = dofile("src/Effect.lua")

local failures = 0

local function check(name, cond, detail)

if cond then

print("ok - " .. name)

else

failures = failures + 1

print("FAIL - " .. name .. ": " .. tostring(detail))

end

end

-- Run forE over [lo, hi) and return the list of indices it visited.

local function visited(lo, hi)

local seen = {}

local function f(i) return function() seen[#seen + 1] = i end end

E.forE(lo)(hi)(f)()

return seen

end

local function showList(t)

local parts = {}

for i = 1, #t do parts[i] = tostring(t[i]) end

return "{" .. table.concat(parts, ", ") .. "}"

end

local function eqList(a, b)

if #a ~= #b then return false end

for i = 1, #a do if a[i] ~= b[i] then return false end end

return true

end

--------------------------------------------------------------------------------

-- #78 forE iterates over [lo, hi) (hi exclusive) -----------------------------

do

local got = visited(0, 3)

check("forE 0 3 visits 0,1,2 (hi exclusive)", eqList(got, {0, 1, 2}), "got " .. showList(got))

end

do

local got = visited(1, 5)

check("forE 1 5 visits 1,2,3,4", eqList(got, {1, 2, 3, 4}), "got " .. showList(got))

end

do

local got = visited(2, 2)

check("forE n n is an empty range (zero iterations)", #got == 0, "got " .. showList(got))

end

do

local got = visited(5, 3)

check("forE lo>hi is empty", #got == 0, "got " .. showList(got))

end

--------------------------------------------------------------------------------

-- foreachE iterates the whole array 1..#as (sanity: NOT off-by-one) ----------

do

local seen = {}

local function f(x) return function() seen[#seen + 1] = x end end

E.foreachE({10, 20, 30})(f)()

check("foreachE visits every element", eqList(seen, {10, 20, 30}), "got " .. showList(seen))

end

--------------------------------------------------------------------------------

if failures > 0 then error(failures .. " regression check(s) failed") end

print("purescript-lua-effect: all FFI regression checks passed")