iskm/learnxinyminutes-docs
1
0
Fork 0
mirror of https://github.com/adambard/learnxinyminutes-docs.git synced 2024-12-23 09:41:36 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

[standard-ml/en-en] Removing syntax errors and fixing solve2 function

Browse Source
This commit is contained in:
Simon Shine 2013-12-03 07:27:29 +01:00
parent 02b8d51897
commit 699dc938e9
1 changed files with 9 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
standard-ml.html.markdown
View File

@ -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