fdd5aec172
This refactors and improves the `#eval` command, introducing some new
features.
* Now evaluated results can be represented using `ToExpr` and pretty
printing. This means **hoverable output**. If `ToExpr` fails, it then
tries `Repr` and then `ToString`. The `eval.pp` option controls whether
or not to try `ToExpr`.
* There is now **auto-derivation** of `Repr` instances, enabled with the
`pp.derive.repr` option (default to **true**). For example:
```lean
inductive Baz
| a | b
#eval Baz.a
-- Baz.a
```
It simply does `deriving instance Repr for Baz` when there's no way to
represent `Baz`. If core Lean gets `ToExpr` derive handlers, they could
be used here as well.
* The option `eval.type` controls whether or not to include the type in
the output. For now the default is false.
* Now things like `#eval do return 2` work. It tries using
`CommandElabM`, `TermElabM`, or `IO` when the monad is unknown.
* Now there is no longer `Lean.Eval` or `Lean.MetaEval`. These each used
to be responsible for both adapting monads and printing results. The
concerns have been split into two. (1) The `MonadEval` class is
responsible for adapting monads for evaluation (it is similar to
`MonadLift`, but instances are allowed to use default data when
initializing state) and (2) finding a way to represent results is
handled separately.
* Error messages about failed instance synthesis are now more precise.
Once it detects that a `MonadEval` class applies, then the error message
will be specific about missing `ToExpr`/`Repr`/`ToString` instances.
* Fixes a bug where `Repr`/`ToString` instances can't be found by
unfolding types "under the monad". For example, this works now:
```lean
def Foo := List Nat
def Foo.mk (l : List Nat) : Foo := l
#eval show Lean.CoreM Foo from do return Foo.mk [1,2,3]
```
* Elaboration errors now abort evaluation. This eliminates some
not-so-relevant error messages.
* Now evaluating a value of type `m Unit` never prints a blank message.
* Fixes bugs where evaluating `MetaM` and `CoreM` wouldn't collect log
messages.
The `run_cmd`, `run_elab`, and `run_meta` commands are now frontends for
`#eval`.
138 lines
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138 lines
3.7 KiB
Text
prelude
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import Init.System.IO
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import Init.Data.List.Control
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import Init.Data.ToString
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open IO.FS
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def check_eq {α} [BEq α] [Repr α] (tag : String) (expected actual : α) : IO Unit :=
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unless (expected == actual) do
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throw $ IO.userError $
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s!"assertion failure \"{tag}\":\n expected: {repr expected}\n actual: {repr actual}"
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def test : IO Unit := do
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let xs : ByteArray := ⟨#[1,2,3,4]⟩;
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let fn := "foo.txt";
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withFile fn Mode.write fun h => do
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h.write xs;
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h.write xs;
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pure ();
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let ys ← withFile "foo.txt" Mode.read $ fun h => h.read 10;
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check_eq "1" (xs.toList ++ xs.toList) ys.toList;
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withFile fn Mode.append fun h => do
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h.write ⟨#[5,6,7,8]⟩;
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pure ();
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withFile "foo.txt" Mode.read fun h => do
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let ys ← h.read 10
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check_eq "2" [1,2,3,4,1,2,3,4,5,6] ys.toList
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let ys ← h.read 2
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check_eq "3" [7,8] ys.toList
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let ys ← h.read 2
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check_eq "5" [] ys.toList
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pure ()
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#guard_msgs in
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#eval test
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def test2 : IO Unit := do
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let fn1 := "bar2.txt";
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let fn2 := "foo2.txt";
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let xs₀ : String := "⟨[₂,α]⟩";
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let xs₁ := "⟨[6,8,@]⟩";
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let xs₂ := "/* Handle.getLine : Handle → IO Unit */" ++
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"/* The line returned by `lean_io_prim_handle_get_line` */" ++
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"/* is truncated at the first \'\\0\' character and the */" ++
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"/* rest of the line is discarded. */";
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-- multi-buffer line
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withFile fn1 Mode.write $ fun _h => pure ();
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withFile fn1 Mode.write $ fun h => do
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h.putStr xs₀
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h.putStrLn xs₀
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h.putStrLn xs₂
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h.putStrLn xs₁
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withFile fn2 Mode.write $ fun h => h.putStr "overwritten"
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rename fn1 fn2
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let ys ← withFile fn2 Mode.read $ fun h => h.getLine;
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IO.println ys;
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check_eq "1" (xs₀ ++ xs₀ ++ "\n") ys;
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IO.println ys;
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withFile fn2 Mode.append $ fun h => do
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{ h.putStrLn xs₁;
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pure () };
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let ys ← withFile fn2 Mode.read $ fun h => do
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{ let ys ← (List.iota 4).mapM $ fun i => do
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{ let ln ← h.getLine;
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IO.println i;
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IO.println ∘ repr $ ln;
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pure ln };
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pure ys };
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IO.println ys;
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let rs := [xs₀ ++ xs₀ ++ "\n", xs₂ ++ "\n", xs₁ ++ "\n", xs₁ ++ "\n"];
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check_eq "2" rs ys;
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let ys ← readFile fn2;
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check_eq "3" (String.join rs) ys;
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pure ()
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/--
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info: ⟨[₂,α]⟩⟨[₂,α]⟩
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⟨[₂,α]⟩⟨[₂,α]⟩
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4
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"⟨[₂,α]⟩⟨[₂,α]⟩\n"
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3
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"/* Handle.getLine : Handle → IO Unit *//* The line returned by `lean_io_prim_handle_get_line` *//* is truncated at the first '\\0' character and the *//* rest of the line is discarded. */\n"
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2
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"⟨[6,8,@]⟩\n"
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1
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"⟨[6,8,@]⟩\n"
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[⟨[₂,α]⟩⟨[₂,α]⟩
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, /* Handle.getLine : Handle → IO Unit *//* The line returned by `lean_io_prim_handle_get_line` *//* is truncated at the first '\0' character and the *//* rest of the line is discarded. */
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, ⟨[6,8,@]⟩
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, ⟨[6,8,@]⟩
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]
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-/
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#guard_msgs in
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#eval test2
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def test3 : IO Unit := do
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let fn3 := "foo3.txt"
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let xs₀ := "abc"
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let xs₁ := ""
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let xs₂ := "hello"
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let xs₃ := "world"
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withFile fn3 Mode.write $ fun _h => do {
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pure ()
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}
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let ys ← lines fn3
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IO.println $ repr ys
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check_eq "1" ys #[]
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withFile fn3 Mode.write $ fun h => do
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h.putStrLn xs₀
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h.putStrLn xs₁
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h.putStrLn xs₂
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h.putStrLn xs₃
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let ys ← lines fn3
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IO.println $ repr ys
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check_eq "2" ys #[xs₀, xs₁, xs₂, xs₃]
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pure ()
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/--
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info: #[]
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#["abc", "", "hello", "world"]
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-/
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#guard_msgs in
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#eval test3
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def test4 : IO Unit := do
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let fn4 := "foo4.txt"
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withFile fn4 Mode.write fun _h => do pure ();
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let ys ← withFile fn4 Mode.read $ fun h => h.read 1;
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check_eq "1" [] ys.toList
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let ys ← withFile fn4 Mode.read $ fun h => h.read 1;
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check_eq "2" [] ys.toList
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#guard_msgs in
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#eval test4
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