Add format and printf string format functions (#401)

* Add format and printf string format functions

* Macro correctly

Author: chrisrink10

src/basilisp/core.lpy

@@ -1862,6 +1862,22 @@
        ~@(next forms))
     x))
 
+;;;;;;;;;;;;;;;;;;;;;;
+;; String Functions ;;
+;;;;;;;;;;;;;;;;;;;;;;
+
+(import* os)
+
+(defn format
+  "Format a string as by Python's `%` operator."
+  [fmt & args]
+  (if (= 1 (count args))
+    (let [arg (first args)]
+      (if (or (map? arg) (py-dict? arg))
+        (operator/mod fmt (python/dict arg))
+        (operator/mod fmt arg)))
+    (operator/mod fmt (python/tuple args))))
+
 ;;;;;;;;;;;;;;;;;;;;;;
 ;; Output Utilities ;;
 ;;;;;;;;;;;;;;;;;;;;;;
@@ -1882,6 +1898,19 @@
   []
   (.flush *out*))
 
+(defn newline
+  "Write a platform specific newline to *out*."
+  []
+  (.write *out* os/linesep)
+  nil)
+
+(defmacro with-in-str
+  "Evaluate body with *in* bound to a io.StringIO instance containing the
+  string s."
+  [s & body]
+  `(binding [*in* (io/StringIO ~s)]
+     ~@body))
+
 (defmacro with-out-str
   "Capture the contents of text sent to *out* and return the contents as a
   string."
@@ -1991,6 +2020,13 @@
   (with-out-str
     (apply println args)))
 
+(defn printf
+  "Prints formatted output as per format.
+
+  Does not append a newline."
+  [fmt & args]
+  (print (apply format fmt args)))
+
 ;;;;;;;;;;;;;;;;;;;;
 ;; REPL Utilities ;;
 ;;;;;;;;;;;;;;;;;;;;
@@ -2805,7 +2841,7 @@
 
 (import* abc)
 
-(defmulti ^:private munge
+(defmulti munge
   "Munge the input value into a Python-safe string. Converts keywords and
   symbols into strings as by `name` prior to munging. Returns a string."
   python/type)
@@ -2822,6 +2858,10 @@
   [s]
   (basilisp.lang.util/munge s))
 
+(def namespace-munge
+  "Convert a Basilisp namespace name to a valid Python name."
+  munge)
+
 (defn gen-interface
   "Generate and return a new Python interface (abstract base clase).