gen version using dune not Makefile

Author: yasunariw

Makefile

@@ -5,12 +5,9 @@ default: build
 start:
 	dune exec -- ./src/monorobot.exe
 
-build: gen_version
+build:
 	dune build src/monorobot.exe
 
-gen_version:
-	./gen_version.sh
-
 test:
 	dune runtest
 
@@ -23,5 +20,4 @@ fmt:
 	dune build @fmt --auto-promote
 
 clean:
-	rm -f src/version.ml
 	dune clean

src/dune

@@ -4,3 +4,9 @@
  (preprocess
   (pps lwt_ppx))
  (public_name monorobot))
+
+(rule
+ (targets version.ml)
+ (deps (universe) gen_version.sh)
+ (action
+  (run "./gen_version.sh")))

gen_version.sh renamed to src/gen_version.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 VERSION=$(git describe --always --tags --dirty=+M)
-cat > src/version.ml <<- EOF
+cat > version.ml <<- EOF
 (* do not edit; generated by gen_version.sh *)
 
 let current = "$VERSION"