Ast_uncurry_gen (melange.Melange_ppx_lib.Ast_uncurry

val to_uncurry_fn : 
  Melange_compiler_libs.Location.t ->
  Melange_compiler_libs.Ast_mapper.mapper ->
  Asttypes.arg_label ->
  Melange_compiler_libs.Parsetree.pattern ->
  Melange_compiler_libs.Parsetree.expression ->
  Melange_compiler_libs.Parsetree.expression_desc

function can only take one argument, that is the reason we did not adopt it syntax:

fun [@bs] pat pat1-> body

to_uncurry_fn (fun pat -> (fun pat1 -> ... body))

val to_method_callback : 
  Melange_compiler_libs.Location.t ->
  Melange_compiler_libs.Ast_mapper.mapper ->
  Asttypes.arg_label ->
  Melange_compiler_libs.Parsetree.pattern ->
  Melange_compiler_libs.Parsetree.expression ->
  Melange_compiler_libs.Parsetree.expression_desc

syntax:

fun [@bs.this] obj pat pat1 -> body