Extempore

Tested against extempore version 0.8.7.

Download the latest Extempore from the project releases page on Github.

Assuming you've started extempore and have the LFE REPL running, as previously described, you will have been automatically connected to the Extempore TCP server. As such, you're ready to start living coding!

There are several ways to do this from LFE:

  1. From an LFE-managed REPL supporting native Extempore syntax,
  2. From an LFE-managed REPL with hybrid Extempore and LFE support, and
  3. From LFE itself (limited Extempore support)

The Extempore REPL

At the LFE prompt, start up the Extempore REPL:

lfe> (undertone.repl.extempore:start)
extempore>

Once at the extempore> prompt, you will be able to enter native Extempore expressions (Scheme and xtlang). These will be passed to the Extempore TCP server as-is (executed asynchronously and non-blocking).

Additionally, you may call other supported functions. To see the list of supported REPL function, type (help):

extempore> (help)

The Extempore undertone REPL

Built-in functions:

(call body) -- make an explicitly blocking call to Extempore, with 'body' being
               a valid Extempore expression
(check-xt)  -- check on the status of Extempore (no response indicates a health
               problem, possibly requiring a restart of the 'extempore' binary)
(eom)       -- alias for '(term)'
(exit)      -- alias for '(quit)'
(h)         -- alias for '(help)'
(help)      -- display this information
(quit)      -- quit the Extempore REPL and return to the LFE REPL
(run file)  -- load the code in the given file and run in Extempore
(term)      -- send message-terminating character sequence to force Extempore
               end-of-message (useful when troubleshooting)
(version)   -- display all the version info for undertone

Extempore support:

All S-expressions other than the ones listed above will be treated as Extempore
Scheme / xtlang code and sent to the Extempore TCP server (compiler service) as
an asynchronous call (no result, no output printed). If you would like to block
on particular calls and see their return values, be sure to use the '(call ...)'
REPL function.

Most (if not all) of the official Extempore examples should work without modification in this REPL.

The Undertone REPL

TBD

Native LFE

Note that only a limited number of Exempore forms are supported from within LFE right now.

Load the appropriate Extempore files into the server and the LFE macros into the current REPL session:

(xt:sys-load "examples/sharedsystem/setup.xtm")
(include-lib "undertone/include/xt-patterns.lfe")

Play an ascending scale using the second synthesizer that comes with Extempore:

(/> 'ascending-scale 4 0 (play 'syn2 '@1 80 'dur) (scale 4 8))

Note that the Extempore syntax for this is :>, a character combination not supported in LFE symbols, so /> was settled upon instead. Similarly, below you will see // used in LFE as an analog for the :| used in Extempore.

Then change the tempo:

(set-tempo! 72)

You can stop the synth in two ways -- changing 'play' form to the 'stop' form while keeping the remaining body the same (this is useful for live coding scenarios): 

(// 'ascending-scale 4 0 (play 'syn2 '@1 80 'dur) (scale 4 8))

or by calling the 'stop' form using just the pattern name you defined in the 'play' form:

(// 'ascending-scale)