AFL  A Functional LanguageIntroductionAs the name implies AFL is a functional language. The goal of creating AFL was to create an easy to parse functional language and help me refurbish my PHP knowledge. :) Use the table of contents below to find out what's available, how to use things, what can be done and what can't. You may also want to try out AFL code snippets available from a drop down at this page AFL  A Functional Language Inbuilt functionsAFL provides inbuilt functions to perform following operations:
Math Functions+ VAR VAR Sum of two numbers.  VAR VAR Subtraction of two numbers. / VAR VAR Division of two number  result is float. \ VAR VAR Integer Division. % VAR VAR Modulus of two numbers. * VAR VAR Product of two numbers. Examples:/ 24 2 * 7 9  2 10 % 4 3 \ 10 3Output: 12 63 8 1 3 Boolean Functions&& VAR VAR Boolean AND  VAR VAR Boolean OR. ^ VAR VAR Exclusive OR. ! VAR Boolean NOT. Examples:&& 1 0  1 0 ^ 1 1 ! 0Output: 0 1 0 1 Bitwise Functions& VAR VAR Bitwise AND.  VAR VAR Bitwise OR. ~ VAR Complement. << VAR VAR Left shift
>> VAR VARRight shift Examples: & 4 3  4 3 ~ 4 << 4 1 >> 4 1Output: 0 7 5 8 2 Comparison Functions< VAR VAR Less than. > VAR VAR Greater than. <= VAR VAR Less than OR equal to. >= VAR VAR Greater than OR equal to. == VAR VAR Equal to. != VAR VAR Not equal to. Examples:< 4 9 > 4 9 <= 4 9 >= 4 9 == 4 9 != 4 9Output: 1 0 1 0 0 1 User defined functions
Defining/creating functions f argument(s) = expression Where 'f' is the name of the function followed by space separated list of arguments the function accepts. A function may accept ZERO or more arguments. Types of arguments : There are three type of arguments in AFL
Passing functions as arguments : You may even pass functions as arguments. (Think of it like passing a function pointer in C, or a function referance in other languages.) See the 'map' function below for an example how it is done. Examples:i = 10 f n = + n 1 sum a b = + a b map i f @list = f i @list pi = / 22 7 g a b c = + (* a c) (* b c)
Calling/using functions i f 10 sum 2 3 map 5 sum [1,2,3] (pi) g (i) 7 8 In the above examples parentheses around 'pi' are optional. But while calling function 'g' with 'i' as one of the argument, you need to enclose 'i' with parentheses. This is required so that function 'i' gets called and its value is used as the first argument of function 'g'.
Simulating IF conditions for a function F n = 2n  1 IF n = 0 To define such a function in AFL you write the following code f n = * 2 n f 0 = 1 So to simulate IF conditions for a function, you provide as many definitions for the function as needed to meet the given criteria. Appropriate function will be called based on the argument being passed, when the function is invoked. List Expansion.. END_VALUE Create list with values 0 to END_VALUE .. START_VALUE END_VALUE Create list with values START_VALUE to END_VALUE .. START_VALUE END_VALUE STEP Create list with values between START_VALUE and END_VALUE with difference of STEP from start to end. Examples:.. 10 .. 1 10 .. 1 10 2Output: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] [1, 3, 5, 7, 9] List Builder@@ INITIAL_LIST : NEXT_VALUE : CONDITION Build a list starting with inital value, next value @@ INITIAL_LIST : NEXT_LIST_ITEM : NEXT_VALUE : CONDITION Build a list starting with inital value, next value By default list builder token appends the next list item to the list. You can prepend the next list item by using '@^' to build a list. '@$' is a synonym for '@@' which mean append to list. NEXT_VALUE
This is the expression or a function which will calculate the next value for building the list and for the CONDITION part.  #10 1The value prefixed with '#' will be used as the starting value for the list builder. CONDITION
This result of the CONDITION determines whether list building continues or stops. If the CONDITION expression results in a False value, list building is stopped. If the CONDITION expression results in a True value, list building continues. > # 0 NEXT_LIST_ITEM This section, if present, calculates the next value that will be put into the list being built. Like the CONDITION expression, NEXT_LIST_ITEM expression too needs to have at least ONE argument as the symbol '#', which will be replaced with the results of evaluation of NEXT_VALUE expression. Example: * # 2 Example of 3TUPLE List Builder @@ [] :  #10 1 : > # 0 The above code will output: [ 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 ] Example of 4TUPLE List Builder @$ [] : * # 2 :  #10 1 : > # 0 The above code will output: [ 20, 18, 16, 14, 12, 10, 8, 6, 4, 2 ] Note that we can use '@$' in place of '@@'. They both mean append new items at the end of list. Example of 4TUPLE Prepend List Builder @^ [100, 200] : + # 2 :  #10 2 : > # 0 The above code will output: [ 4, 6, 8, 10, 12, 100, 200 ] Apart from the prepend list builder, the examples also shows the use of nonempty list as initial value. List operators@& LIST List length : This operator computes the length of the list. @# VAR LIST
List Item: Use this operator to extract a list item out of a list. @& [1,2,3,4] @# 2 [1,2,3,4]Output: 4 3 Comments
You may insert comments into AFL code by starting a line with a semicolon ';'. ; This is a comment
f a b = + a b ; Comments like these won't work, they need to be on a line of their own.
Complex expressionsYou may use output of one function as input of another function to create complex expressions. Example:f a = + a 1 g b = + a 2 f (g 7) Notice how we used parentheses around 'g 7' to tell AFL that this is a function call, evaluate it first. Had we not used parentheses, AFL would have complained about not being able to found a matching signature for 'f g 7', i.e. a function named f accepting two arguments.
i = 10 f a = * a 2 f (i) f 3 As you can see 'i' is a function which takes no arguments and always returns 10. To pass its result to 'f' we need to enclose it inside parentheses as shown. Literal values can be passed without parentheses. You may use as many deeply nested functions using parentheses, as the need may be. Example:+ 1 (+ 2 (+ 3 4)) Limitations and special notesThere are some intentional limitations to the AFL language to keep it simple. Most of them are quite obvious from the documentation above. The things that are not obvious are listed here.
The snippets Even though there are certain limitaions to AFL, still there are some cool and nifty things that can be done. You may have a look at snippets on the Demo page to see few examples. Use the drop down to select an example and click on the execute button to try it out. And do experiment with the snippet, trying out different values and/or editing some code to see how things are working!

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