diff --git a/pydoit/doit_ex.py b/pydoit/doit_ex.py
new file mode 100644
index 0000000..5e9fb73
--- /dev/null
+++ b/pydoit/doit_ex.py
@@ -0,0 +1,133 @@
+from fn import _
+from helpers import D, F, fifo, to_fifo, group_fastqs, swap_ext
+from glob import glob1
+#NOTE:
+'''
+ they're dropping python2 support in next release
+ it's by modification time
+ the output will always have to be created as a fifo, but not the input
+ to wrap "targets" in fifo
+ 'task_dep' does exist
+'''
+
+'''Options'''
+class Opts(object): pass
+opts = Opts()
+opts.cutadapt = { 'headcrop' : 33 }
+opts.bwa = { 'threads' : 1, 'keep_temp' : False}
+opts.tagreads = { 'CA' : "Foo"}
+opts.freebayes = { 'observations' : 5, 'haplotype_length' : 50}
+
+'''Input files'''
+DIR="."
+opts.ref = F("ref.fasta")
+R1s, R2s, unpaireds =  group_fastqs(DIR)
+R1, R2, unpaired, paired, merged, consensus = map(F, ["R1", "R2", "unpaired", "paired", "merged", "consensus"])
+sffs = glob1(DIR, "*.sff")
+unpaireds += [swap_ext(sff, 'fastq') for sff in sffs]
+
+'''example tasks'''
+def task_index_ref():
+    return { 'targets' : [opts.ref.fai],
+             'file_dep' : [opts.ref],
+             'actions' : ['bwa index %(dependencies)'] }
+
+def task_sff2fastq(): 
+    @fifo('o')
+    def convert_sff(i, o): SeqIO.convert(i, 'sff', o, 'fastq')
+
+    for sff in sffs:
+        yield {'target' : [swap_ext(sff, 'fastq')],
+               'file_deps' : [sff],
+               'actions' : convert_sff}
+
+''' examples of programmatically created tasks 
+tasks must be wrapped in functions starting with `task_`
+(so using lambda: dict) '''
+
+
+def cutadapt_paired(dependencies, targets, quality):
+    sh.cutadapt(o=targets[0], p=targets[1], q="{0},{0}".format(quality), *dependencies)
+
+def cutadapt_up(dependencies, targets, quality):
+    sh.cutadapt(q=quality, o=targets[0], *dependencies) 
+    #'actions': ["cutadapt %(dependencies)"] # not work
+
+def gen_cutdapt(fqs):
+   func = cutadapt_paired if len(fqs) > 1 else cutadapt_up
+   return { 'targets'  : map(_.cutadapt, fqs),
+            'file_dep' : fqs, 
+            'actions' : [to_fifo(func, 'targets'), [], opts.cutadapt] }
+
+def task_run_cutadapt():
+    for fqs in zip(R1s, R2s) + unpaireds:
+        yield gen_cutdapt(fqs) 
+
+
+merge_files = D({
+    'actions' : ['cat %(dependencies) > %(targets)']})
+
+# _.cutdadapt = lambda x: x.cudadapt
+# `.assoc` is like `.update` but returns a new dictionary without changing the old one
+task_R1 = lambda: merge_files.assoc(file_dep=map(_.cutadapt, R1s), targets=R1.fastq)
+task_R2 = lambda: merge_files.assoc(file_dep=map(_.cutadapt, R2s), targets=R2.fastq)
+task_unpaired  = lambda: merge_files.assoc(file_dep=map(_.cutadapt, unpaireds), targets=unpaired.fastq)
+
+
+@fifo('targets')
+def bwa_map(dependencies, targets, threads, keep_temp):
+   '''`dependencies` and `targets` are lists auto-provided by
+   pydoit with `file_deps` and `targets` from the task dictionary.
+   The keyword arguments are provided by the dictionary in the
+   third element of `'actions'`, in this case `opts.bwa`'''
+   sh.bwa.mem(dependencies, t=threads, _out=targets[0])
+
+mapping =   D({'file_dep' : [opts.ref],
+             'actions' : [bwa_map, [], opts.bwa]}) #opts.bwa here sends the kwargs to `bwa_map`
+
+#`.apply(key=func)` applies the func to the value at that key
+
+mapping_up = mapping.apply(file_dep = _ + [unpaired.fastq]).assoc(targets=[unpaired.bam])
+mapping_paired = mapping.apply(file_dep = _ + [R1.fastq, R2.fastq]).assoc(targets=[paried.bam])
+task_maping_up = lambda : mapping_up
+task_maping_paired = lambda : mapping_paired 
+
+def task_merge_bam():
+    return { 'targets' : [unsorted.bam]
+             'file_dep' : [paired.bam, unpaired.bam], #'task_dep' : 'mapping',
+             'actions' : ['mkfifo %(targets)', 'samtools merge %(targets) %(dependencies)']}
+
+def make_task(target, dep, action):
+    return { 'targets' : [target], 'file_dep' : [dep], 'actions' : [action] }
+
+task_sort_bam = lambda : make_task(merged.bam, unsorted.bam, 'mkfifo %(targets) && samtools sort %(dependencies) > %(targets)')
+task_index_bam = lambda : make_task(merged.bam.bai, merged.bam, 'samtools index %(dependencies)')
+task_tag_bam = lambda : { 'file_dep' : [merged.bam],
+                          'actions' : ['tagreads %(dependencies) --CN %s' % opts.tagreads['CN'] ] }
+# this is screwed up because the tagged bam file may not be sorted. Should swap out `tagreads` for 
+# something that creates a new file, it's simpler
+# also that doesn't play well with fifo
+
+@fifo('targets')
+def run_freebayes(dependencies, targets, haplotype_length, observations):
+    sh.freebayes(dependencies[0], f=dependencies[1], 
+            haplotype_length=haplotype_length, C=observations, _out=targets[0])
+
+def task_freebayes(): 
+    return {  'targets' : [merged.bam.vcf]
+              'file_dep' : [merged.bam, opts.ref, ref.fasta.fai]
+              'task_dep' : ['tag_bam']
+              'actions' : [run_freebayes, [], opts.freebayes] }
+
+def task_consensus():
+    def TODO(dependecies, targets):
+        pass
+    return { 'targets' : [consensus.fasta]
+             'file_dep' : [merged.bam.vcf, opts.ref]
+             'actions' : [TODO] }
+
+'''
+actions take kwargs. so add the dict associated with a task (e.g., ngs_filter)
+dynamically, based on func name #
+dy of task-creators are executed even if the task is not going to be executed.
+'''
diff --git a/pydoit/helpers.py b/pydoit/helpers.py
new file mode 100644
index 0000000..ff10ccb
--- /dev/null
+++ b/pydoit/helpers.py
@@ -0,0 +1,86 @@
+import os
+from glob import glob# ls =  partial(glob.glob1, ".")
+from functools import wraps, partial
+from toolz import compose
+forward = compose(sorted, partial(glob1, pattern="*_R1_*"))
+reverse = compose(sorted, partial(glob1, pattern="*_R2_*"))
+def _unpaired(dir): return set(glob1(dir, '*')) - set(forward(dir) + reverse(dir))
+def group_fastqs(dir): return forward(dir), reverse(dir), _unpaired(dir)
+
+class F (str):
+  """represents a file"""
+  def __div__(self, other):
+      return F(os.path.join(self, other))
+
+  def __rdiv__(self, other):
+      return F(os.path.join(other, self))
+
+  def __getattr__(self, ext):
+    try:
+      return super(self.__class__, self).__getattr__(ext)
+    except:
+      return F('{0}.{1}'.format(self, ext))
+
+def assoc_all(d, **kwargs):
+    dict = d.copy()
+    for k,v in kwargs.items():
+        dict[k] = v
+    return dict
+
+def update_all(d, **kwargs):
+    dict = d.copy()
+    for k,f in kwargs.items():
+        dict[k] = f(dict[k])
+    return dict
+
+class D (dict):
+  """dictionary with extra methods"""
+
+  def assoc(self, **kwargs):
+    return assoc_all(self, **kwargs)
+
+  def apply(self, **kwargs):
+    return update_all(self, **kwargs)
+
+def to_fifo(func, *argnames):  #works as composition
+    code = func.func_code
+    names = code.co_varnames[:code.co_argcount]
+    @wraps(func)
+    def decorated(*args,**kwargs):
+        for argname in argnames:
+            argval = kwargs.get(argname, args[names.index(argname)])
+#            try:
+#                argval = args[names.index(argname)]
+#            except ValueError:
+#                argval = kwargs[argname]
+            if hasattr(argval, '__iter__'):
+                for f in argval:
+                    os.mkfifo(f)
+            else:
+                os.mkfifo(argval)
+
+        return func(*args, **kwargs)
+    return decorated
+
+#decorator
+def fifo(*argnames):
+    def decorated(func):
+        return to_fifo(func, *argnames)
+    return decorated
+
+fwd, rev = glob("*_R1_*.fastq"), glob("*_R2_*.fastq")
+ext = lambda s: s.split('.')[-1]
+swap_ext = lambda s, ext: '.'.join(s.split('.')[:-1] + [ext])
+
+
+#{
+#    cutadapt_up : filter_up,
+#    filter_up : get_input_up,
+#    cutadapt_paired : filter_paired,
+#    filter_paired : get_input_paired,
+#    bwa_up : cutadapt_up,
+#    bwa_paired : cutadapt_paired,
+#    samtools_merge : [bwa_up, bwa_paired],
+#    samtools_index : samtools_merge,
+#    freebayes : [samtools_index
+#
diff --git a/pydoit/requirements.txt b/pydoit/requirements.txt
new file mode 100644
index 0000000..0848421
--- /dev/null
+++ b/pydoit/requirements.txt
@@ -0,0 +1,3 @@
+doit
+fn
+toolz