19 files changed, 267 insertions, 4 deletions

diff --git a/samples/euler/001.bruijn b/samples/euler/001.bruijn
new file mode 100644
index 0000000..1678b58
--- /dev/null
+++ b/samples/euler/001.bruijn
@@ -0,0 +1,10 @@
+:import std/Combinator .
+:import std/List .
+:import std/Math .
+
+solve [∑(crit <#> ({ (+0) → --0 }))]
+	crit φ m ((\mod (+3)) → zero?) ((\mod (+5)) → zero?)
+
+:test ((solve (+10)) =? (+23)) ([[1]])
+
+main [solve (+1000)]
diff --git a/samples/euler/002.bruijn b/samples/euler/002.bruijn
new file mode 100644
index 0000000..a0b614c
--- /dev/null
+++ b/samples/euler/002.bruijn
@@ -0,0 +1,13 @@
+:import std/Combinator .
+:import std/List .
+:import std/Math .
+
+# could be arbitrary >34, chosen by manual min search
+lim (+34)
+
+solve [∑(crit <#> (take lim fibs))]
+	crit φ [[0 1 0]] even? (\les? 0)
+
+:test ((solve (+4000)) =? (+3382)) ([[1]])
+
+main [solve (+4000000)]
diff --git a/samples/euler/003.bruijn b/samples/euler/003.bruijn
new file mode 100644
index 0000000..0dc016d
--- /dev/null
+++ b/samples/euler/003.bruijn
@@ -0,0 +1,8 @@
+:import std/Combinator .
+:import std/Math .
+
+solve factors → lmax
+
+:test ((solve (+13195)) =? (+29)) ([[1]])
+
+main [solve (+600851475143)]
diff --git a/samples/euler/004.bruijn b/samples/euler/004.bruijn
new file mode 100644
index 0000000..e04cb4c
--- /dev/null
+++ b/samples/euler/004.bruijn
@@ -0,0 +1,19 @@
+# TODO: This has serious performance problems
+
+:import std/Combinator .
+:import std/List .
+:import std/Math .
+
+# palindrome? S.number→string → [S.eq? S.<~>0 0]
+
+palindrome? [y [[[&[[>?2 (4 (3 ⋅ (+10) + 0) 1) (3 =? 5)]] (quot-rem 0 (+10))]]] (+0) 0]
+
+# combs [[S.concat-map [S.map (mul 0) ({ 0 → 1 })] ({ ((+10) ** --1) → 0 })] --((+10) ** 0)]
+
+solve [[y [[[0 =? 3 1 rec]]] empty ((+10) ** --1)] ((+10) ** 0)] → lmax
+	rec 2 (comb ++ 1) ++0
+		comb y [[[0 =? 6 1 (2 ([palindrome? 0 (0 : 2) 2] (3 ⋅ 0)) ++0)]]] empty 0
+
+:test ((solve (+2)) =? (+9009)) ([[1]])
+
+main [solve (+3)]
diff --git a/samples/euler/005.bruijn b/samples/euler/005.bruijn
new file mode 100644
index 0000000..8455510
--- /dev/null
+++ b/samples/euler/005.bruijn
@@ -0,0 +1,8 @@
+:import std/Math .
+:import std/List .
+
+solve [foldr1 lcm ({ (+1) → 0 })]
+
+:test ((solve (+10)) =? (+2520)) ([[1]])
+
+main [solve (+20)]
diff --git a/samples/euler/006.bruijn b/samples/euler/006.bruijn
new file mode 100644
index 0000000..75582c7
--- /dev/null
+++ b/samples/euler/006.bruijn
@@ -0,0 +1,10 @@
+:import std/Combinator .
+:import std/Math .
+
+solve [|(sum-of-squares - square-of-sum)]
+	sum-of-squares ∑ (+1) → 0 | (\pow (+2))
+	square-of-sum (∑ (+1) → 0 | i) ** (+2)
+
+:test ((solve (+10)) =? (+2640)) ([[1]])
+
+main [solve (+100)]
diff --git a/samples/euler/007.bruijn b/samples/euler/007.bruijn
new file mode 100644
index 0000000..6d05451
--- /dev/null
+++ b/samples/euler/007.bruijn
@@ -0,0 +1,11 @@
+# TODO: Write faster primes function
+
+:import std/Combinator .
+:import std/Math .
+:import std/List .
+
+solve dec → (\index primes)
+
+:test ((solve (+6)) =? (+13)) ([[1]])
+
+main [solve (+10001)]
diff --git a/samples/euler/009.bruijn b/samples/euler/009.bruijn
new file mode 100644
index 0000000..be21d9e
--- /dev/null
+++ b/samples/euler/009.bruijn
@@ -0,0 +1,17 @@
+:import std/Combinator .
+:import std/Logic .
+:import std/Math .
+:import std/List .
+
+# solve' [head <#> lst]
+# 	check (2 + 1 + 0 =? 3) ⋀? ((0 ** (+2)) + (1 ** (+2)) =? (2 ** (+2))) (true : (2 ⋅ 1 ⋅ 0)) {}false
+# 	lst concat-map [concat-map [map [check] ({ (+1) → --0 })] ({ (+1) → --0 })] ({ (+1) → 0 })
+
+solve [head <#> lst] → head → tail
+	check [[[[[2 + 1 + 0 =? 7 (true : (2 ⋅ 1 ⋅ 0)) {}false]]] a b c]] (1 ** (+2)) (0 ** (+2))
+		a 1 - 0
+		b (+2) ⋅ 3 ⋅ 2
+		c 1 + 0
+	lst concat-map [map [check] ({ (+1) → --0 })] ({ (+2) → (sqrt 0) })
+
+main [solve (+1000)]
diff --git a/samples/euler/012.bruijn b/samples/euler/012.bruijn
new file mode 100644
index 0000000..e644a03
--- /dev/null
+++ b/samples/euler/012.bruijn
@@ -0,0 +1,12 @@
+# TODO: Find faster algorithm
+
+:import std/Combinator .
+:import std/Math .
+
+factors [[y [[[(1 <? 3) (2 ++1 (0 + (=?(4 % 1) (+2) (+0)))) 0]]] (+1) (+0)] ++(sqrt 0)]
+
+solve [y [[[(factors 1) >? 3 1 (2 (1 + 0) ++0)]]] (+0) (+0)]
+
+:test ((solve (+5)) =? (+28)) ([[1]])
+
+main [solve (+500)]
diff --git a/samples/euler/013-input.bruijn b/samples/euler/013-input.bruijn
new file mode 100644
index 0000000..43b568e
--- /dev/null
+++ b/samples/euler/013-input.bruijn
@@ -0,0 +1,100 @@
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diff --git a/samples/euler/013.bruijn b/samples/euler/013.bruijn
new file mode 100644
index 0000000..a37d74f
--- /dev/null
+++ b/samples/euler/013.bruijn
@@ -0,0 +1,8 @@
+# it's really interesting that (take (+10)) makes the entire computation 10s faster
+# laziness ftw!
+
+:import std/Combinator .
+:import std/String .
+:import std/Math .
+
+main trim → lines → (map string→number) → sum → number→string → (take (+10))
diff --git a/samples/euler/014.bruijn b/samples/euler/014.bruijn
new file mode 100644
index 0000000..5e0e906
--- /dev/null
+++ b/samples/euler/014.bruijn
@@ -0,0 +1,15 @@
+# TODO: Really slow
+
+:import std/Combinator .
+:import std/List .
+:import std/Math .
+:import std/Number/Binary .
+
+hailstone-length y [[[0 =? (+1b) 1 go]]] (+0b)
+	go =²?0 (2 ++1 /²0) (2 ++1 (↑¹0 + 0))
+
+solve [max-by (compare ⋔ hailstone-length) (take 0 (iterate inc (+1b)))]
+
+:test ((solve (+1000)) =? (+871b)) ([[1]])
+
+main [solve (+1000000)]
diff --git a/samples/euler/016.bruijn b/samples/euler/016.bruijn
new file mode 100644
index 0000000..b5ede83
--- /dev/null
+++ b/samples/euler/016.bruijn
@@ -0,0 +1,10 @@
+# TODO: digit-sum/quot-rem is still the bottleneck
+
+:import std/Combinator .
+:import std/Math .
+
+solve (pow (+2)) → digit-sum
+
+:test ((solve (+15)) =? (+26)) ([[1]])
+
+main [solve (+1000)]
diff --git a/std/List.bruijn b/std/List.bruijn
index 488c131..ed16530 100644
--- a/std/List.bruijn
+++ b/std/List.bruijn
@@ -510,6 +510,11 @@ iterate z [[[rec]]] ⧗ (a → a) → a → (List a)
 :test (take (+5) (iterate i (+4))) (take (+5) (repeat (+4)))
 :test (take (+0) (iterate ++‣ (+0))) (empty)
 
+# enumerate list
+enumerate zip (iterate ++‣ (+0)) ⧗ (List a) → (List (Pair Number a))
+
+:test (enumerate "abc") (((+0) : 'a') : (((+1) : 'b') : {}((+2) : 'c')))
+
 # calculates all fixed points of given function as a list
 y* [[[0 1] <$> 0] xs] ⧗ (List a) → (List b)
 	xs [[1 <! ([[1 2 0]] <$> 0)]] <$> 0
diff --git a/std/Math.bruijn b/std/Math.bruijn
index e2a9466..82a787d 100644
--- a/std/Math.bruijn
+++ b/std/Math.bruijn
@@ -213,11 +213,18 @@ characteristic-primes ki : (ki : (sieve s0)) ⧗ (List Bool)
 	s0 [[[ki : (0 2)]]]
 
 # prime number sequence
-primes L.map fst (L.filter snd (L.zip (L.iterate ++‣ (+0)) characteristic-primes)) ⧗ (List Number)
+primes L.map fst (L.filter snd (enumerate characteristic-primes)) ⧗ (List Number)
 
 # slower but cooler prime number sequence
 primes* L.nub ((…≠?… (+1)) ∘∘ gcd) (L.iterate ++‣ (+2)) ⧗ (List Number)
 
+# prime factors
+factors \divs primes ⧗ Number → (List Number)
+	divs y [[&[[&[[3 ⋅ 3 >? 4 case-1 (=?0 case-2 case-3)]] (quot-rem 2 1)]]]]
+		case-1 4 >? (+1) {}4 empty
+		case-2 3 : (5 1 (3 : 2))
+		case-3 5 4 2
+
 # π as a list of decimal digits
 # translation of unbounded spigot algorithm by Jeremy Gibbons
 # TODO: faster!
diff --git a/std/Monad.bruijn b/std/Monad.bruijn
index 97291eb..0dae29e 100644
--- a/std/Monad.bruijn
+++ b/std/Monad.bruijn
@@ -37,6 +37,9 @@ sequence foldr (lift-m2 cons) {}empty ⧗ (List (M a)) → (M (List a))
 
 >‣ [sequence ∘∘ 0]
 
+# traverses list based on modifier
+traverse sequence ∘∘ map ⧗ (a → (M b)) → (N a) → (M (N b))
+
 # performs action n times
 replicate-m >replicate ⧗ Number → (M a) → (M (List a))
 
diff --git a/std/Number.bruijn b/std/Number.bruijn
index b2f3631..25a1f6c 100644
--- a/std/Number.bruijn
+++ b/std/Number.bruijn
@@ -9,9 +9,9 @@
 # the following functions are only here because of recursive imports of list/ternary
 
 # converts number to list of its digits
-number→list [=?0 {}(+0) (z [[rec]] 0)] ⧗ Number → (List Number)
+number→list [=?0 {}(+0) <~>(z [[[rec]]] empty 0)] ⧗ Number → (List Number)
 	rec =?0 case-end case-rec
-		case-rec (1 (0 / (+10))) ; (0 % (+10))
+		case-rec &[[4 (0 : 3) 1]] (quot-rem 0 (+10))
 		case-end empty
 
 :test (number→list (+0)) ({}(+0))
diff --git a/std/Number/Ternary.bruijn b/std/Number/Ternary.bruijn
index 5e93c66..3695740 100644
--- a/std/Number/Ternary.bruijn
+++ b/std/Number/Ternary.bruijn
@@ -500,10 +500,11 @@ double-shift [[[[[left : right]] (force 2 1) (force 2 0)]]]
 	left force 4 ((mst* 0) ↑ (+0) + (↑⁰1))
 	right force 4 ↑⁰0
 
-# efficient quotient/remainder implementation for balanced ternary
+# "efficient" quotient/remainder implementation for balanced ternary
 # technique by Douglas W. Jones
 # algorithm originally intended for fixed-width numbers (=> ugly hacks with force+log3)
 # TODO: remove the final `huh` correction step (probably some off-by-one bug?)
+# TODO: not actually that efficient right now
 quot-rem [[[[[z [[[[rec]]]] 1 (+0) 4]]] <?0 (max (log3 1) (log3 0)) 0]] ⧗ Number → Number → (Pair Number Number)
 	rec =?2 huh (double-shift 5 1 0 [[compare-case eq gt lt 1 (+0)]])
 		huh (>?1 ⋀? 6) ⋁? (<?1 ⋀? \6) (--0 : (1 + 7)) (0 : 1)
diff --git a/std/String.bruijn b/std/String.bruijn
index e1f4f4b..6ffd1f4 100644
--- a/std/String.bruijn
+++ b/std/String.bruijn
@@ -110,6 +110,12 @@ number→string (map C.number→char) ∘ number→list ⧗ Number → String
 
 :test (number→string (+123)) ("123")
 
+# trims whitespace from the beginning and end of a string
+trim w b (reverse ∘ (drop-while (ni? "\t\r\n "))) ⧗ String → String
+
+:test (trim "  ab  ") ("ab")
+:test (trim "\t\r\nab\t\r\n") ("ab")
+
 # splits string by newline character
 lines z [[rec]] ⧗ String → (List String)
 	rec build (break (B.eq? '\n') 0)