From dba4ea41ce332f6945e61f580aee675a50a9b237 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Fri, 7 Jun 2024 13:31:29 +0200
Subject: Some more work on monads

---
 samples/fun/rng-state.bruijn | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 samples/fun/rng-state.bruijn

(limited to 'samples/fun/rng-state.bruijn')

diff --git a/samples/fun/rng-state.bruijn b/samples/fun/rng-state.bruijn
new file mode 100644
index 0000000..795bad1
--- /dev/null
+++ b/samples/fun/rng-state.bruijn
@@ -0,0 +1,27 @@
+# MIT License, Copyright (c) 2024 Marvin Borner
+# generates three pseudo-random integers using a state monad
+# printf <seed:number> | bruijn rng-state.bruijn
+
+:import std/Combinator .
+:import std/String .
+:import std/Number .
+:import std/Monad/State .
+
+max (+1000)
+
+rand [[[0 1 1]] rng]
+	rng (+1103515245) ⋅ 0 + (+12345) % max
+
+rand-bool map even? rand
+
+# accumulating bind (reversed)
+triple1 rand >>= (rand >>= (rand >>= [[[[[0 3 [0 3 [0 3 [[0]]]]]]]]]))
+
+:test ((triple1 (+50) [[1]]) =? (+745)) ([[1]])
+
+# normal bind
+triple2 rand >>= [rand >>= [rand >>= [[[0 4 [0 4 [0 4 [[0]]]]]]]]]
+
+:test ((triple2 (+50) [[1]]) =? (+595)) ([[1]])
+
+main string→number → triple2
-- 
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