From 101ed72e9f97a8f68b5f678854c992dff18d8f9f Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Sun, 8 Sep 2019 14:00:56 +0200
Subject: Init: basic command line abstraction for fish’s complete
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---
 pkgs/profpatsch/dhallsh/List/filterOptional.dhall | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 pkgs/profpatsch/dhallsh/List/filterOptional.dhall

(limited to 'pkgs/profpatsch/dhallsh/List')

diff --git a/pkgs/profpatsch/dhallsh/List/filterOptional.dhall b/pkgs/profpatsch/dhallsh/List/filterOptional.dhall
new file mode 100644
index 00000000..810599b0
--- /dev/null
+++ b/pkgs/profpatsch/dhallsh/List/filterOptional.dhall
@@ -0,0 +1,23 @@
+let filterOptional
+	: ∀(a : Type) → ∀(b : Type) → (a → Optional b) → List a → List b
+	=   λ(a : Type)
+	  → λ(b : Type)
+	  → λ(f : a → Optional b)
+	  → λ(l : List a)
+	  → List/build
+		b
+		(   λ(list : Type)
+		  → λ(cons : b → list → list)
+		  → λ(nil : list)
+		  → List/fold
+			a
+			l
+			list
+			(   λ(x : a)
+			  → λ(xs : list)
+			  → Optional/fold b (f x) list (λ(opt : b) → cons opt xs) xs
+			)
+			nil
+		)
+
+in  filterOptional
-- 
cgit 1.4.1