From 89719ce8e61f50ffae4a880c4897f4ad4290a9cd Mon Sep 17 00:00:00 2001
From: Takafumi Arakaki <aka.tkf@gmail.com>
Date: Mon, 20 Jul 2020 17:48:30 -0700
Subject: [PATCH 1/2] Add `definite` and `asmissing`

---
 src/Maybe.jl          |  4 +++-
 src/docs/asmissing.md | 23 +++++++++++++++++++++++
 src/docs/definite.md  | 18 ++++++++++++++++++
 src/extras.jl         |  5 +++++
 4 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 src/docs/asmissing.md
 create mode 100644 src/docs/definite.md

diff --git a/src/Maybe.jl b/src/Maybe.jl
index 039262c..b16af3b 100644
--- a/src/Maybe.jl
+++ b/src/Maybe.jl
@@ -23,11 +23,13 @@ Since there is no name clash with `Base` API, `using Maybe.Extras`
 imports the API defined in `Maybe.Extras`.
 """
 baremodule Extras
-export getnested, ifnothing, maybe, defaultto
+export asmissing, defaultto, definite, getnested, ifnothing, maybe
 function maybe end
 function ifnothing end
 function defaultto end
 function getnested end
+function definite end
+function asmissing end
 end
 
 const X = Extras
diff --git a/src/docs/asmissing.md b/src/docs/asmissing.md
new file mode 100644
index 0000000..61e8dcd
--- /dev/null
+++ b/src/docs/asmissing.md
@@ -0,0 +1,23 @@
+    Maybe.Extras.asmissing(x)
+
+Translate `Union{Nothing,T,Some{T},Some{Some{T}},...}` to
+`Union{T,Missing}`.
+
+This is a shorthand of `something(definite(x), missing)`.
+
+# Examples
+```julia
+julia> using Maybe.Extras
+
+julia> asmissing(1)
+1
+
+julia> asmissing(nothing)
+missing
+
+julia> asmissing(Some(Some(1)))
+1
+
+julia> asmissing(Some(Some(nothing)))
+missing
+```
diff --git a/src/docs/definite.md b/src/docs/definite.md
new file mode 100644
index 0000000..6f052de
--- /dev/null
+++ b/src/docs/definite.md
@@ -0,0 +1,18 @@
+    Maybe.Extras.definite(x)
+
+Unwrap `Some` recursively and obtain a non-`Some` value.  The returned
+value is `nothing` if `x` is `nothing` or `nothing` wrapped in `Some`
+(possibly multiple times).
+
+# Examples
+```julia
+julia> using Maybe.Extras
+
+julia> definite(Some(Some(Some(1))))
+1
+
+julia> definite(Some(Some(Some(nothing))))
+
+julia> something(definite(Some(Some(nothing))), 2)
+2
+```
diff --git a/src/extras.jl b/src/extras.jl
index 0cb8d67..9108c08 100644
--- a/src/extras.jl
+++ b/src/extras.jl
@@ -26,3 +26,8 @@ Maybe.Extras.defaultto(c) = Maybe.Extras.ifnothing(() -> c)
 @inline Maybe.Extras.getnested(x, k, keys...) =
     Maybe.Extras.getnested(@something(Maybe.get(x, k), return), keys...)
 @inline Maybe.Extras.getnested(x) = Some(x)
+
+Maybe.Extras.definite(x) = x
+Maybe.Extras.definite(x::Some) = Maybe.Extras.definite(something(x))
+
+Maybe.Extras.asmissing(x) = something(Maybe.Extras.definite(x), missing)

From 52e278efba171e2d1b3e15335c937a1a39cfefbd Mon Sep 17 00:00:00 2001
From: Takafumi Arakaki <aka.tkf@gmail.com>
Date: Mon, 3 Aug 2020 23:15:57 -0700
Subject: [PATCH 2/2] Add `frommissing`

---
 src/Maybe.jl  | 3 ++-
 src/extras.jl | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Maybe.jl b/src/Maybe.jl
index b16af3b..d1996f7 100644
--- a/src/Maybe.jl
+++ b/src/Maybe.jl
@@ -23,13 +23,14 @@ Since there is no name clash with `Base` API, `using Maybe.Extras`
 imports the API defined in `Maybe.Extras`.
 """
 baremodule Extras
-export asmissing, defaultto, definite, getnested, ifnothing, maybe
+export asmissing, defaultto, definite, frommissing, getnested, ifnothing, maybe
 function maybe end
 function ifnothing end
 function defaultto end
 function getnested end
 function definite end
 function asmissing end
+function frommissing end
 end
 
 const X = Extras
diff --git a/src/extras.jl b/src/extras.jl
index 9108c08..efd0a0b 100644
--- a/src/extras.jl
+++ b/src/extras.jl
@@ -31,3 +31,6 @@ Maybe.Extras.definite(x) = x
 Maybe.Extras.definite(x::Some) = Maybe.Extras.definite(something(x))
 
 Maybe.Extras.asmissing(x) = something(Maybe.Extras.definite(x), missing)
+
+Maybe.Extras.frommissing(::Missing) = nothing
+Maybe.Extras.frommissing(x) = Some(x)