Utilities

All functions are located in the com.biffweb namespace.

(pprint & args)

Alias of clojure.pprint/pprint

(start-system init)

Starts a system from an initial system map.

Stores the system in the com.biffweb/system atom. Returns the contents of the
atom. See https://biffweb.com/docs/reference/system-composition

(refresh)

Stops the system, refreshes source files, and restarts the system.

The system is stopped by calling all the functions in (:biff/stop
@com.biffweb/system). (:biff/after-refresh @system) is a fully-qualified
symbol which will be resolved and called after refreshing. See
https://biffweb.com/docs/reference/system-composition

(use-config {:keys [biff/config], :or {config "config.edn"}, :as ctx})

Reads config from an edn file and merges into sys.

The config file's contents should be a map from environments to config keys
and values, for example:

{:prod {:host "example.com"
        :port 8080}
 :dev {:merge [:prod]
       :host "localhost"}}

The current environment should be stored in the BIFF_ENV environment variable.
The default value is `prod`. To inherit config from other environments, set
:merge to a sequence of environment keys.

(sh & args)

Runs a shell command.

Returns the output if successful; otherwise, throws an exception.

(assoc-some m & kvs)

Like assoc, but skips kv pairs where the value is nil.

(pred-> x pred f)

Convenience fn for (cond-> x (pred x) f)

(join sep xs)

Returns a sequence where the elements of coll are separated by sep.

(safe-merge & ms)

Like merge, but throws an exception if any maps share keys.

(normalize-email email)

Normalizes an email address to make future lookups easier.

Trims leading and trailing whitespace and converts to lower case. Returns nil
if the email is empty after trimming.

(use-when f & components)

Passes the system map to components only if (f system) is true.

See https://biffweb.com/docs/reference/system-composition

(sha256 string)

Returns the SHA256 hash of string.

(base64-encode bytes)

Converts a byte array to a base64 string.

(base64-decode string)

Converts a base64 string to a byte array.

(anomaly? x)

Returns true if x is an anomaly.

See https://github.com/cognitect-labs/anomalies

(anom category & [message & [opts]])

Constructs an anomaly.

Example: (anom :incorrect
               "Invalid parameter"
               {:info "x should be an integer"})

See https://github.com/cognitect-labs/anomalies

(select-ns-as m ns-from ns-to)

Selects and renames keys from m based on the namespace.

Examples:

(select-ns-as {:foo/a 1, :foo.bar/b 2, :baz/c 3} 'foo 'quux)
=> {:quux/a 1, :quux.bar/b 2}

(select-ns-as {:foo/a 1, :foo.bar/b 2, :baz/c 3} 'foo nil)
=> {:a 1, :bar/b 2}

(catchall & body)

Wraps body in (try ... (catch Exception _ nil))

(catchall-verbose & body)

Like catchall, but prints exceptions.

(letd bindings & body)

Like let, but transparently wraps all bindings with delay.

Examples:

(macroexpand-1 '(letd [a 1]
                  a))
=> (let [a (delay 1)]
     @a)

(letd [a (do (println "a evaluated")
             1)
       {:keys [b]} (do (println "b evaluated")
                       {:b 2})
       [_ _ c] (do (println "c evaluated")
                   [1 2 3])]
  (if (even? b)
    a
    c))
=>
(out) b evaluated
(out) a evaluated
1

(fix-print & body)

Ensures that print output doesn't get swallowed by e.g. an editor nrepl plugin.

Binds *out*, *err* and *flush-on-newline* to their root values.

(fix-print
  (println "hello"))

(eval-files! {:keys [biff/eval-paths], :or {eval-paths ["src"]}})

Evaluates any modified files and their dependents via clojure.tools.namespace.

(add-libs)

Loads new dependencies in deps.edn via tools.deps.alpha.

Ensures that a DynamicClassLoader is available so that this works even when
not evaluated from the repl. See
https://ask.clojure.org/index.php/10761/clj-behaves-different-in-the-repl-as-opposed-to-from-a-file

(delete-old-files
 {:keys [dir exts age-seconds], :or {age-seconds 30}, :as opts})

Deletes files descended from the given directory that are older than a given threshold.

dir:          A path to a directory.
age-seconds:  Files will only be deleted if it's been at least this number of seconds since they
              were last modified. Defaults to 30 seconds.
exts:         An optional collection of filename extentions. If provided, files will only be
              deleted if they end with one of the extentions.

For example:
(delete-old-files {:dir "target/resources/public"
                   :exts [".html"]})