From fc06b0a33357352c99c5b1e41789c15920daac73 Mon Sep 17 00:00:00 2001
From: Matthew Honnibal <honnibal+gh@gmail.com>
Date: Thu, 5 Oct 2017 21:52:28 -0500
Subject: [PATCH] Fix training when hist_size==0

---
 spacy/_ml.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/spacy/_ml.py b/spacy/_ml.py
index 6223715b5..d6e745f22 100644
--- a/spacy/_ml.py
+++ b/spacy/_ml.py
@@ -257,6 +257,8 @@ class Embed(Model):
 
 def HistoryFeatures(nr_class, hist_size=8, nr_dim=8):
     '''Wrap a model, adding features representing action history.'''
+    if hist_size == 0:
+        return layerize(noop())
     embed_tables = [Embed(nr_dim, nr_class, column=i, name='embed%d')
                     for i in range(hist_size)]
     embed = concatenate(*embed_tables)