diff options
Diffstat (limited to 'red.html.markdown')
| -rw-r--r-- | red.html.markdown | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/red.html.markdown b/red.html.markdown index 6d10fe8f..34c4bcd9 100644 --- a/red.html.markdown +++ b/red.html.markdown @@ -34,7 +34,8 @@ brackets can be filled with useful information about this script or program: the author's name, the filename, the version, the license, a summary of what the program does or any other files it needs. The red/System header is just like the red header, only saying "red/System" and not "red". - +``` +```red Red [] ;this is a commented line @@ -50,7 +51,7 @@ comment { ; no need to restrict this to a 'main' function. ; Valid variable names start with a letter and can contain numbers, -; variables containing only capital A thru F and numbers and ending with 'h' +; variables containing only capital A through F and numbers and ending with 'h' ; are forbidden, because that is how hexadecimal numbers are expressed in Red ; and Red/System. @@ -102,7 +103,8 @@ type? my-integer integer! ; A variable can be initialized using another variable that gets initialized -; at the same time. +; at the same time. Initialize here refers to both declaring a variable and +; assigning a value to it. i2: 1 + i1: 1 ; Arithmetic is straightforward @@ -112,12 +114,12 @@ i2 * i1 ; result 2 i1 / i2 ; result 0 (0.5, but truncated towards 0) ; Comparison operators are probably familiar, and unlike in other languages -; you only need a single '=' sign for comparison. +; you only need a single '=' sign for comparison. Inequality is '<>' like in Pascal. ; There is a boolean like type in Red. It has values true and false, but also ; the values on/off or yes/no can be used 3 = 2 ; result false -3 != 2 ; result true +3 <> 2 ; result true 3 > 2 ; result true 3 < 2 ; result false 2 <= 2 ; result true @@ -127,22 +129,22 @@ i1 / i2 ; result 0 (0.5, but truncated towards 0) ; Control Structures ; ; if -; Evaluate a block of code if a given condition is true. IF does not return -; any value, so cannot be used in an expression. +; Evaluate a block of code if a given condition is true. IF returns +; the resulting value of the block or 'none' if the condition was false. if a < 0 [print "a is negative"] ; either ; Evaluate a block of code if a given condition is true, else evaluate an ; alternative block of code. If the last expressions in both blocks have the ; same type, EITHER can be used inside an expression. -either a < 0 [ +either a > 0 [ + msg: "positive" +][ either a = 0 [ msg: "zero" ][ msg: "negative" ] -][ - msg: "positive" ] print ["a is " msg lf] @@ -150,20 +152,20 @@ print ["a is " msg lf] ; There is an alternative way to write this ; (Which is allowed because all code paths return a value of the same type): -msg: either a < 0 [ +msg: either a > 0 [ + "positive" +][ either a = 0 [ "zero" ][ "negative" ] - ][ - "positive" ] print ["a is " msg lf] ; until ; Loop over a block of code until the condition at end of block, is met. -; UNTIL does not return any value, so it cannot be used in an expression. +; UNTIL always returns the 'true' value from the final evaluation of the last expression. c: 5 until [ prin "o" @@ -214,7 +216,7 @@ The Red/System language specification can be found [here](http://static.red-lang To learn more about Rebol and Red join the [chat on Gitter](https://gitter.im/red/red). And if that is not working for you drop a mail to us on the [Red mailing list](mailto: red-langNO_SPAM@googlegroups.com) (remove NO_SPAM). -Browse or ask questions on [Stack Overflow](stackoverflow.com/questions/tagged/red). +Browse or ask questions on [Stack Overflow](https://stackoverflow.com/questions/tagged/red). Maybe you want to try Red right away? That is possible on the [try Rebol and Red site](http://tryrebol.esperconsultancy.nl). |