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`.
92 lines
2.1 KiB
Text
92 lines
2.1 KiB
Text
import Lean.CoreM
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open Lean
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structure MyState :=
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(trace_state : TraceState := {})
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(s : Nat := 0)
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abbrev M := CoreM
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def tst1 : M Unit :=
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do trace[module] (m!"hello" ++ MessageData.nest 9 (m!"\n" ++ "world"));
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trace[module.aux] "another message";
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pure ()
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def tst2 (b : Bool) : M Unit :=
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withTraceNode `module (fun _ => return "message") do
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tst1;
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trace[bughunt] "at test2";
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if b then throwError "error";
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tst1;
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pure ()
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partial def ack : Nat → Nat → Nat
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| 0, n => n+1
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| m+1, 0 => ack m 1
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| m+1, n+1 => ack m (ack (m+1) n)
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def slow (b : Bool) : Nat :=
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ack 4 (cond b 0 1)
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def tst3 (b : Bool) : M Unit :=
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do withTraceNode `module.slow (fun _ => return m!"slow: {slow b}") do {
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tst2 b;
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tst1
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};
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trace[bughunt] "at end of tst3";
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-- Messages are computed lazily. The following message will only be computed
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-- if `trace.slow is active.
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trace[slow] (m!"slow message: " ++ toString (slow b))
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-- This is true even if it is a monad computation:
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trace[slow] (m!"slow message: " ++ (← pure (toString (slow b))))
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def run (x : M Unit) : M Unit :=
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withReader
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(fun ctx =>
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-- Try commenting/uncommeting the following `setBool`s
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let opts := ctx.options;
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let opts := opts.setBool `trace.module true;
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-- let opts := opts.setBool `trace.module.aux false;
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let opts := opts.setBool `trace.bughunt true;
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-- let opts := opts.setBool `trace.slow true;
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{ ctx with options := opts })
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(tryCatch (tryFinally x printTraces) (fun _ => IO.println "ERROR"))
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/--
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info: [module] message
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[module] hello
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world
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[bughunt] at test2
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ERROR
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---
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info: [module] message
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[module] hello
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world
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[bughunt] at test2
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-/
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#guard_msgs in
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#eval run (tst3 true)
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/--
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info: [module] message
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[module] hello
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world
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[bughunt] at test2
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[module] hello world
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[module] hello
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world
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[bughunt] at end of tst3
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---
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info: [module] message
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[module] hello
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world
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[bughunt] at test2
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[module] hello
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world
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[module] hello
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world
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[bughunt] at end of tst3
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-/
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#guard_msgs in
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#eval run (tst3 false)
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