Run using bash, lazily compile

docker/Dockerfile

@@ -1,5 +1,7 @@
 FROM nimlang/nim:alpine
 
+RUN apk update && apk add bash
+
 ADD entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 

docker/entrypoint.sh

@@ -1,8 +1,10 @@
-#!/bin/sh
+#!/bin/bash
 
 cd /code
 
 if [ -f "day$1.nim" ]; then
-    HOME=/tmp nim c --opt:speed -d:release day$1.nim >/dev/null 2>&1
+    if [ ! -f "day$1" -o "day$1.nim" -nt "day$1" ]; then
+        HOME=/tmp nim c --opt:speed -d:release day$1.nim >/dev/null 2>&1
+    fi
     time ./day$1
 fi

run.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-IMAGE=csmith/aoc-2018-04
+IMAGE=csmith/aoc-2018-05
 
 docker image inspect $IMAGE >/dev/null 2>&1
 if [ $? -ne 0 ]