7ed716f904
This PR improves the error messages produced by invalid projections and field notation. It also adds a hint to the "function expected" error message noting the argument to which the term is being applied, which can be helpful for debugging spurious "function expected" messages actually caused by syntax errors. --------- Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
109 lines
2.6 KiB
Text
109 lines
2.6 KiB
Text
/-!
|
||
# Tests for generalized field notation through aliases and "top-level" dot notation
|
||
https://github.com/leanprover/lean4/issues/3031
|
||
-/
|
||
|
||
/-!
|
||
Alias dot notation. There used to be a different kind of alias dot notation;
|
||
in the following example, it would have looked for an argument of type `Common.String`.
|
||
Now it looks for one of type `String`, allowing libraries to add "extension methods" from within their own namespaces.
|
||
-/
|
||
def Common.String.a (s : String) : Nat := s.length
|
||
|
||
export Common (String.a)
|
||
|
||
/-- info: String.a "x" : Nat -/
|
||
#guard_msgs in #check String.a "x"
|
||
/-- info: String.a "x" : Nat -/
|
||
#guard_msgs in #check "x".a
|
||
|
||
/-!
|
||
Declarations take precedence over aliases
|
||
-/
|
||
def String.a (s : String) : Nat := s.length + 100
|
||
/-- info: "x".a : Nat -/
|
||
#guard_msgs in #check "x".a
|
||
/-- info: 100 -/
|
||
#guard_msgs in #eval "".a
|
||
|
||
/-!
|
||
Private declarations take precedence over aliases
|
||
-/
|
||
private def String.b (s : String) : Nat := 0
|
||
def Common.String.b (s : String) : Nat := 1
|
||
export Common (String.b)
|
||
/-- info: 0 -/
|
||
#guard_msgs in #eval "".b
|
||
|
||
/-!
|
||
Multiple aliases is an error
|
||
-/
|
||
def Common.String.c (s : String) : Nat := 0
|
||
def Common'.String.c (s : String) : Nat := 0
|
||
export Common (String.c)
|
||
export Common' (String.c)
|
||
/--
|
||
error: Field name `c` is ambiguous: `String.c` has possible interpretations `Common'.String.c`, `Common.String.c`
|
||
-/
|
||
#guard_msgs in #eval "".c
|
||
|
||
/-!
|
||
Aliases work with inheritance
|
||
-/
|
||
namespace Ex1
|
||
structure A
|
||
structure B extends A
|
||
def Common.A.x (_ : A) : Nat := 0
|
||
export Common (A.x)
|
||
/-- info: fun b => A.x b.toA : B → Nat -/
|
||
#guard_msgs in #check fun (b : B) => b.x
|
||
end Ex1
|
||
|
||
/-!
|
||
`open` also works
|
||
-/
|
||
def Common.String.parse (_ : String) : List Nat := []
|
||
|
||
namespace ExOpen1
|
||
/--
|
||
error: Invalid field `parse`: The environment does not contain `String.parse`
|
||
""
|
||
has type
|
||
String
|
||
-/
|
||
#guard_msgs in #check "".parse
|
||
section
|
||
open Common
|
||
/-- info: String.parse "" : List Nat -/
|
||
#guard_msgs in #check "".parse
|
||
end
|
||
section
|
||
open Common (String.parse)
|
||
/-- info: String.parse "" : List Nat -/
|
||
#guard_msgs in #check "".parse
|
||
end
|
||
end ExOpen1
|
||
|
||
|
||
namespace Ex2
|
||
class A (n : Nat) where
|
||
x : Nat
|
||
|
||
/-!
|
||
Incidental fix: `@` for generalized field notation was failing if there were implicit arguments.
|
||
True projections were ok.
|
||
-/
|
||
def A.x' {n : Nat} (a : A n) := a.x
|
||
|
||
/-- info: fun a => a.x' : A 2 → Nat -/
|
||
#guard_msgs in #check fun (a : A 2) => @a.x'
|
||
end Ex2
|
||
|
||
namespace Ex3
|
||
variable (f : α → β) (g : β → γ)
|
||
/-!
|
||
Functions use the "top-level" dot notation rule: they use the first explicit argument, rather than the first function argument.
|
||
-/
|
||
/-- info: g ∘ f : α → γ -/
|
||
#guard_msgs in #check g.comp f
|
||
end Ex3
|