Enable building for GHCJS on Travis, streamline build script

.travis.yml

@@ -21,14 +21,13 @@ env:
     - MATCHING_TESTS=yes
   matrix:
     - GHCVERSION=ghc802 STRICT=false TRACING=false PROFILING=false
-    # - GHCVERSION=ghc802 STRICT=false TRACING=true  PROFILING=false
     - GHCVERSION=ghc802 STRICT=false TRACING=true  PROFILING=true
     - GHCVERSION=ghc822 STRICT=true  TRACING=false PROFILING=false
     - GHCVERSION=ghc822 STRICT=true  TRACING=true  PROFILING=false
     - GHCVERSION=ghc822 STRICT=true  TRACING=true  PROFILING=true
     - GHCVERSION=ghc842 STRICT=false TRACING=false PROFILING=false
-    # - GHCVERSION=ghc842 STRICT=false TRACING=true  PROFILING=false
     - GHCVERSION=ghc842 STRICT=false TRACING=true  PROFILING=true
+    - GHCVERSION=ghcjs NIX_CONF_DIR=$PWD/ghcjs
 
 matrix:
   allow_failures:
@@ -38,7 +37,7 @@ matrix:
     - env: GHCVERSION=ghc822 STRICT=false
 
 script:
-  - nix-build --argstr compiler $GHCVERSION --arg doProfiling $PROFILING --arg doTracing $TRACING --arg doStrict $STRICT
+  - bash -xe build.sh
 
 branches:
   only:

build.sh

@@ -0,0 +1,19 @@
+#!/bin/bash -xe
+
+set -euo pipefail
+IFS=$'\n\t'
+
+GHCVERSION=${GHCVERSION:-ghc822}
+STRICT=${STRICT:-false}
+TRACING=${TRACING:-false}
+PROFILING=${PROFILING:-false}
+
+if [ "$GHCVERSION" = "ghcjs" ]; then
+    exec nix-build ghcjs
+else
+    exec nix-build                              \
+        --argstr compiler $GHCVERSION           \
+        --arg doProfiling $PROFILING            \
+        --arg doTracing $TRACING                \
+        --arg doStrict $STRICT
+fi