A-M baby

Task/Factorial/Smalltalk/factorial-1.st

@@ -0,0 +1,13 @@
+Number extend [
+  my_factorial [
+    (self < 2) ifTrue: [ ^1 ]
+               ifFalse: [ |c|
+                 c := OrderedCollection new.
+                 2 to: self do: [ :i | c add: i ].
+		 ^ (c fold: [ :a :b | a * b ] )
+               ]
+  ]
+].
+
+7 factorial printNl.
+7 my_factorial printNl.

Task/Factorial/Smalltalk/factorial-2.st

@@ -0,0 +1,7 @@
+Number extend [
+  my_factorial [
+    self < 0 ifTrue: [ self error: 'my_factorial is defined for natural numbers' ].
+    self isZero ifTrue: [ ^1 ].
+    ^self * ((self - 1) my_factorial)
+  ]
+].

Task/Factorial/Smalltalk/factorial-3.st

@@ -0,0 +1,10 @@
+  |fac|
+
+  fac := [:n |
+    n < 0 ifTrue: [ self error: 'fac is defined for natural numbers' ].
+    n <= 1
+        ifTrue: [ 1 ]
+        ifFalse: [ n * (fac value:(n - 1)) ]
+  ].
+  fac value:1000.
+].

Task/Factorial/Smalltalk/factorial-4.st

@@ -0,0 +1,4 @@
+| fac |
+fac := [ :n | (1 to: n) inject: 1 into: [ :prod :next | prod * next ] ].
+fac value: 10.
+"3628800"