flan/test/programs/rl-with.flan
Joseph Ferano 25f56c24a8 A begin/end pair that cannot come apart, and what it still cannot promise
vendor/raylib/modes.flan: five macros over the five pairs the package binds
-- with-drawing, with-mode-2d, with-mode-3d, with-texture-mode,
with-scissor-mode. A second file with no declare-c in it, split out on
vector.flan's reasoning: raylib.flan is the package's statement about C and
nothing here names C, so nothing here can be made wrong by raylib changing.

Each expands to (do (begin-... args) body... (end-...)) -- the calls the
author used to type, in the order they typed them. No let, no gensym: nothing
binds a name, so there is nothing for a caller's name to collide with.

What it removes is the End* that is missing, wrong, or no longer beside its
Begin*. What it cannot remove is a body leaving through the unwind path: a
return or an invoke-restart skips the rest of the do and the End* with it.
defer is the obvious fix and is refused inside a loop body, which is where a
pair always lives -- checked, not assumed. So sand.flan's discipline stays:
keep the restart boundary outside the pair.

35 call sites converted across examples/ and sand.flan. The one left is
core-scissor-test.flan, whose Begin and End sit in two separate `when`s with
the drawing between them -- a conditional pair is a shape a bracketing macro
cannot express.

test/programs/rl-with.flan covers with-scissor-mode, which no example can,
with a frame function unreachable from main so it needs no libraylib;
rl-with-reject.flan is the arity half.
2026-09-13 18:00:35 +07:00

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;;;; The raylib package's five begin/end macros, expanded.
;;;;
;;;; They cannot be *run* here. Every one of them brackets calls that need a
;;;; window and a GL context, so a headless case can only assert what the
;;;; expansion is, not what it draws — which is the whole of what a macro
;;;; over a pair can get wrong. The four examples/ uses of with-drawing and
;;;; friends already prove they compile; what this adds is with-scissor-mode,
;;;; which no example can use (examples/core-scissor-test.flan turns its
;;;; scissor on and off from a flag, so its Begin and its End sit inside two
;;;; separate `when`s and there is no body to wrap). The arity refusals are
;;;; rl-with-reject.flan, beside this.
;;;;
;;;; [frame] is deliberately not reached from [main]. lib/reach.ml answers the
;;;; link from the checked program, so an unreachable frame means this case
;;;; needs no libraylib to run and goes in the suite unconditionally — while
;;;; [check] still walks every line of it, which is where a wrong expansion
;;;; would show.
(import rl "vendor:raylib")
(defn frame [cam rl/Camera2D cam3 rl/Camera3D target rl/RenderTexture2D] ()
(rl/with-drawing
(rl/clear-background rl/raywhite)
(rl/with-mode-2d cam
(rl/draw-rectangle 0 0 10 10 rl/red))
(rl/with-mode-3d cam3
(rl/draw-fps 0 0))
(rl/with-scissor-mode 10 10 100 100
(rl/draw-rectangle 0 0 320 240 rl/blue)
(rl/draw-text "clipped" 20 20 10 rl/black))
(rl/draw-fps 10 10))
;; Off-screen, outside the frame, which is where a render texture belongs.
(rl/with-texture-mode target
(rl/clear-background rl/blank)))
(defn main [] i32
(println "expanded")
0)