Each let will create a scope and symbol resolution is done inside the let where the symbol is resolved. However, this time Clojure resolves a to "AAA", instead of aaa. Like previous example, Clojure tries to resolve a. user> ( let ( let ( println a ))) AAA nil a is bound to "aaa", so "aaa" is printed in your terminal. user> ( let ( println a )) aaa nilĬlojure tries to evaluate a because it needs to pass the value to println. When Clojure tries to resolve a symbol, the resolution will be done in the scope of the symbol. The binding will be immediately available, so each binding can see the prior bindings. user> ( let ( println ( str "God also said let there be " l_d ))) God also said let there be light and darkness nil user=> ( let ( println ( str "God said let there be " l )) ( println ( str "God also said let there be " d ))) God said let there be light God also said let there be darkness nil This behavior is very similar to private variable in other programming languages. You cannot resolve the symbol outside the let. user=> ( println l ) CompilerException : Unable to resolve symbol : l in this context, compiling : ( NO_SOURCE_PATH :1:1 ) Let takes a vector which takes a symbol in the first element and a value in the second element. Let user=> ( let ( println ( str "God said let there be " l ))) God said let there be light nil When we try to resolve symbols that are not bound to anything, Clojure complains with the exception. You can obtain bound values by resolving symbols. If you don't prepend a ' single quote, you are telling Clojure to resolve the symbol. user> ( def a "aaaaa" ) # 'user/a user> ( println a ) aaaaa nil user> ( println b ) CompilerException : Unable to resolve symbol : b in this context, compiling : ( NO_SOURCE_PATH :1:1 ) We are doing this here because we want to treat symbols as data in order to pass them to type function. ' will prevent a form from being evaluated. user> ( type 'a ) user> ( type 'b ) user> ( type 'my-cool-function ) user> ( type 'nyncat ) a b my-cool-function nyncat: they are all symbols in Clojure. Symbols are used to bind names to values. However, we call the mapping between names and values binding in Clojure. Giving names to values is called assignment in many programming languages. You can think of form as something that returns a value. It's also called expression in a general sense, but there is no real problem to use them interchangeably.
Using clojure with nedit code#
The entire line of the code (.) is called a form in Clojure. We call the invocation of function applying the function to data in Clojure or other functional programming language. Here, we invoke the function println with the argument Hello, world!. Our first Clojure code is, of course, printing "Hello, world!". Hopefully, this page helps you learning functional programming and starting to write Clojure! Hello, world! user=> ( println "Hello, world!" ) Hello, world! nil user> "h" "h" user> 100 100 user> true true I have paid careful attention to make this page easy to understand for people who don't have experiences with functional programming languages, so please don't hesitate to read this page even if you don't know anything about functional programming. So, I decided to create one while learning Clojure.Ĭlojure is a functional programming language and learning functional programming languages is sometimes hard if you've only had experiences with imperative languages. Recently, I needed to learn this completely new language Clojure but couldn't find what I wanted. These are very basic questions, but enough to start hacking with the new languages. If you take this approach, having many simple code examples are extremely helpful because I can find answers to these questions very easily.ĭoes the language support string interpolation? Rather, I like starting by writing small and dirty code. I don't like reading thick O'Reilly books when I start learning new programming languages.
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