Differences from Clojure

jank is meant to be Clojure, but Clojure itself has no specification. There are differences between Clojure JVM, ClojureScript, Clojure CLR, ClojureDart, and others. Part of being a Clojure is embracing one’s host and being transparent about it. This is where most of the differences come into play.

jank does not try to hide its C++ host. That would defeat the point of being Clojure.

Command line

• You will find no Clojure CLI -X:foo syntax here
• When using jank run or jank run-main, -- is needed to separate args for jank from args for your program
  • Example: jank -I include run test.jank -- a b c

clojure.core

• Baked into the jank binary, not shipped separately
• No nested require support (same as ClojureScript)
• No import
• (hash-map) returns a hash map, not an array map
• aget is a special form
• aset is a macro
• keyword is more strict about valid inputs

Object model

• No stable boxes for small integers (the JVM pre-allocates 1, 2, 3, etc)
• persistent_string is expected to be UTF-8
• No inheritance (currently)
• No records (yet)
• No protocols (yet)
• Sequences
  • Support for in-place operations (fresh-seq, next-in-place)

Compilation model

• Source-only distribution
  • .o files found in JARs will not be used
  • Git deps are an exception here; if someone commits a .o file into a git dep on your module path, jank will load it
• jank uses the term “module path” instead of “class path”
  • We don’t have .class files
  • A module is backed by either a .jank, .cljc or .cpp source file, optionally with a .o file cached for quick loading

Math

• Division by integer 0 is undefined behavior
• Division by floating point 0.0 is well defined