output.txt

["" [[path "" body ["(define (id x)" "    x)"]]] "" [[path "" body ["    (define x 1)" "    <<id>>" "    (id x)"]]] "" [[path "test2.ss" body [" :paddle no" "    (define y 2)" "    <<id>>" "    (id x)"]]] "" [[path "test.ss" body [" :paddle no" "    ;; ok" "    <<test2.ss>>"]]]]

tangle.red

input: {
    Test for tangle.red.

#+NAME: id
#+BEGIN_SRC scheme
(define (id x)
    x)
#+END_SRC

boo

#+BEGIN_SRC scheme
    (define x 1)
    <<id>>
    (id x)
#+END_SRC

yadaydya

#+NAME: test2.ss
#+BEGIN_SRC scheme :tangle test2.ss :paddle no
    (define y 2)
    <<id>>
    (id x)
#+END_SRC

    bla-b;a

#+BEGIN_SRC scheme :tangle test.ss :paddle no
    ;; ok
    <<test2.ss>>
#+END_SRC
}

src-name: ["#+NAME:" any space copy name to newline]
src-path: [":tangle" some space copy path to [space thru newline | newline]]
src-begin: ["#+BEGIN_SRC" thru [src-path | copy path none newline]]
src-end: ["#+END_SRC"]
src-collect: [
  keep (copy name)
  collect keep (reduce ['path (copy path) 'body (split body newline)])
]
src-body: [src-begin copy body to src-end src-collect]
code: [[ src-name | copy name none]  src-body ]
prose: [thru newline]
doc: [some [code | prose] to end]

probe parse input [collect doc]