Joseph Ferano
26c53e0a19
The mechanical half, ahead of the parser change that needs it. tools/unit-return.py
fills the empty slot with () and rewrites Unit as () wherever a type is spelled --
(Fn [i32] Unit), (Map i32 Unit), a return type written out.
Deciding whether a defn already had a return type is the whole difficulty, and
the script does it the way parse.ml did: is_type_form is transcribed rather than
improved, because being identical to the parser it replaces is what makes the
sweep meaning-preserving. It is re-runnable, so the lanes that branched before
this can have the same pass at merge:
python3 tools/unit-return.py .
python3 tools/unit-return.py --in-strings test/test_flan.ml test/test_acceptance.ml \
test/test_session.ml emacs/test-flan-dev.el emacs/test-flan-mode.el
python3 tools/unit-return.py --raw-ml lib/prelude.ml
python3 tools/unit-return.py --in-html web/index.html
-v logs every defn it saw and what it decided, which is how a sweep of 440 sites
gets reviewed at all. Embedded modes pool a file's type declarations across all
its fragments, because a snippet split across concatenation -- decls ^ "(defn f
[s [u8]] Cursor ...)" -- cannot see the names the other half declared; pooled
names count only in bare-symbol position, for the same reason the prelude's do.
A fragment that cuts off mid-form is skipped rather than guessed at. Five sites
in test_flan.ml still needed a hand, and they are in this commit.
Two things ride along because the sweep needs them: parse.ml reads a lone () as
the return type of a function with no body, which was not a shape the old
optional slot could produce; and the map refusals name () rather than Unit, since
that is now the spelling a caller wrote.
18 lines
500 B
Plaintext
18 lines
500 B
Plaintext
(defstruct Cursor
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[src [u8] ; a non-owning slice
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pos i32]) ; no initialiser means zeroed
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(defn peek [c (Ptr Cursor)] u8
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(if (< (.pos c) (len (.src c)))
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(at (.src c) (.pos c))
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0))
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(defn advance [c (Ptr Cursor)] ()
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(set (.pos c) (+ (.pos c) 1))) ; field access derefs one level
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(defn main [] ()
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(let [c (Cursor {.src (bytes "hi")})] ; pos omitted, so pos is 0
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(print (peek (addr c))) (println "")
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(advance (addr c))
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(print (peek (addr c))) (println "")))
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