linked-modules.wat

;; Each of these 4 modules is independently published. Note that, while there is a non-trivial amount of type-y
;; boilerplate, it is proportional in size to only the *direct* dependencies.

(module $A
  (type $Wasi (instance ...))
  (import "wasi" (instance (type $Wasi)))
  (func (export "a") ...)
)

(module $B
  (type $Wasi (instance ...))
  (import "wasi" (instance $wasi (type $Wasi)))
  (import "A:1.x" (module $A
    (import "wasi" (instance (type $Wasi)))
    (export "a" (func))
  ))
  (instance $a (instantiate $A (instance $wasi)))
  (func (export "b") ...)
)

(module $C
  (type $Wasi (instance ...))
  (import "wasi" (instance $wasi (type $Wasi)))
  (import "B:1.x" (module $B
    (import "wasi" (instance $wasi (type $Wasi)))
    (export "b" (func))
  ))
  (instance $b (instantiate $B (instance $wasi)))
  (func (export "c") ...)
)

(module $D
  (type $Wasi (instance ...))
  (import "wasi" (instance $wasi (type $Wasi)))
  (import "C:1.x" (module $C
    (import "wasi" (instance $wasi (type $Wasi)))
    (export "c" (func))
  ))
  (instance $c (instantiate $C (instance $wasi)))
  (func (export "d") ...)
)

;; Invoking 'link' on $D produces the following linked module. Notice that the amount of module-type-y 
;; boilerplate is O(n) where n is the number of transitive dependencies, not O(n^2). Without the
;; wrapper modules, it would be O(n^2).

(module
  (type $Wasi (instance ...))

  (import "A:1.0.0:sha256..." (module $A
    (import "wasi" (instance (type $Wasi)))
    (export "a" (func $a))
  ))
  (import "B:1.0.0:sha256..." (module $B
    (import "wasi" (instance (type $Wasi)))
    (import "A:1.x" (module
      (import "wasi" (instance (type $Wasi)))
      (export "a" (func))
    ))
    (export "b" (func $b))
  ))
  (module $B_wrap
    (import "wasi" (instance $wasi (type $Wasi)))
    (instance $b (instantiate $B (instance $wasi) (module $A)))
    (export "b" (func $b.$b))
  )
  (import "C:1.0.0:sha256..." (module $C
    (import "wasi" (instance (type $Wasi)))
    (import "B:1.x" (module
      (import "wasi" (instance $wasi (type $Wasi)))
      (export "b" (func))
    ))
    (export "c" (func $c))
  ))
  (module $C_wrap
    (import "wasi" (instance $wasi (type $Wasi)))
    (instance $c (instantiate $C (instance $wasi) (module $B_wrap)))
    (export "c" (func $c.$c))
  )
  (import "D:1.0.0:sha256..." (module $D
    (import "wasi" (instance (type $Wasi)))
    (import "C:1.x" (module
      (import "wasi" (instance $wasi (type $Wasi)))
      (export "c" (func))
    ))
    (export "d" (func))
  ))
  (instance $d (instantiate $D (instance $wasi) (module $C_wrap)))
  (export $d)
)