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--- background [2022/04/21 22:01] – [Difficulties to understand Haskell? You are not alone.] f2b216
+++ background [2025/10/08 00:44] (current) – external edit 127.0.0.1
@@ Line 32: / Line 32: @@
 ===== Understanding Haskell =====
-Let's understand how Haskell works?
+Just to imagine how rich Haskell is in terms of abstraction - and to understand how must can be and sometimes has to be understood - enyoy the example below.
+The following shows how 10 primes are evaluated and displayed starting with the one millionth prime number.
   * Example )<sup>1</sup> )<sup>2</sup>:
@@ Line 55: / Line 57: @@
 </code>
-To understand this code (7 lines of code) completely I have to understand the following:
+To understand this code (8 lines of code) completely I have to understand the following:
   - Packets
   - Import
@@ Line 91: / Line 93: @@
 )<sup>1</sup> The code may __**not**__ work with extrem large numbers. I do not know at which conditions the floor function would fail. My calculator says sqrt((1E16x1E16)-1) is 9.999.999.999.999.999,9999999999999999, but sqrt((1E17x1E17)-1) is (1E17)!
+The following code (sieve of Erastothenes) will also work but by far not as fast for large numbers (approximately 100 times slower for the first 20 thousand prime numbers):
+<code Haskell>
+primes = let sieve (n0:lrn) = n0 : sieve [ n | n <- lrn, n `mod` n0 /= 0 ] in sieve [2..]
+</code>
 )<sup>2</sup> The code compiles without any warnings with ghc 8.10.4 and option -Wall.