diff options
Diffstat (limited to 'standard-ml.html.markdown')
| -rw-r--r-- | standard-ml.html.markdown | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/standard-ml.html.markdown b/standard-ml.html.markdown index b586efa5..ab5e4b84 100644 --- a/standard-ml.html.markdown +++ b/standard-ml.html.markdown @@ -199,17 +199,17 @@ val hmm = answer "What is the meaning of life, the universe and everything?" (* Functions can take several arguments by taking one tuples as argument: *) fun solve2 (a : real, b : real, c : real) = - ( Math.sqrt (~b + Math.sqrt(b * b - 4.0*a*c) / (2.0 * a), - Math.sqrt (~b - Math.sqrt(b * b - 4.0*a*c) / (2.0 * a) ) + ( (~b + Math.sqrt(b * b - 4.0*a*c)) / (2.0 * a), + (~b - Math.sqrt(b * b - 4.0*a*c)) / (2.0 * a) ) (* Sometimes, the same computation is carried out several times. It makes sense to save and re-use the result the first time. We can use "let-bindings": *) fun solve2 (a : real, b : real, c : real) = let val discr = b * b - 4.0*a*c - val sqr = Math.sqrt d + val sqr = Math.sqrt discr val denom = 2.0 * a - in (~b + sq / denom, - ~b - sq / denom) end + in ((~b + sqr) / denom, + (~b - sqr) / denom) end (* Pattern matching is a funky part of functional programming. It is an @@ -273,10 +273,10 @@ fun say(col) = raise Fail "Unknown color" (* Datatypes are very often used in combination with pattern matching *) -fun say Red = "You are red!" +fun say Red = "You are red!" | say Green = "You are green!" - | say Blue = "You are blue!" - | _ = raise Fail "Unknown color" + | say Blue = "You are blue!" + | say _ = raise Fail "Unknown color" (* Here is a binary tree datatype *) @@ -321,7 +321,7 @@ val test_poem = readPoem "roses.txt" (* gives [ "Roses are red,", "Violets are blue.", "I have a gun.", "Get in the van." ] *) -~~~~ +``` ## Further learning |