StringTemplate Basics

In the previous section we rendered a template in ghci using the following command

*Main Misc View Text.StringTemplate> do templates <- directoryGroupSafer "templates" ; writeFile "output.html" ( renderTemplateGroup templates [] "templates-dont-repeat-yourself" )

Let's look more carefully at these functions.

The directoryGroupSafer function reads in all *.st type files in a directory, and returns an IO STGroup value, which is basically a group of StringTemplates. It is a modification of the directoryGroup command that comes with Text.StringTemplate package, which ignores email backup files-type files with punctuation, that cause annoyance when using HStringTemplate functions.
*Main Misc View Text.StringTemplate> :t (directoryGroupSafer :: String -> IO (STGroup String))
The actual type of directoryGroupSafer is a little less concrete than the above, and uses type classes.
Our :t command gives directoryGroupSafer a concrete type, and since there's no error, we know it typechecks.
renderTemplateGroup takes an STGroup, some template key/value pairs, and a named template, and renders the template if it is found in the STGroup. If it is not found, an error is returned.
*Main Misc View Text.StringTemplate> :t renderTemplateGroup
renderTemplateGroup :: STGroup String -> [(String, String)] -> String -> String

Next, let's look at a slightly more involved example of StringTemplate usage than we've seen so far.

The controller: myFavoriteAnimal, in src/ControllerBasic.hs
a snip:
renderTemplateGroup templates
[("favoriteAnimal", "Tyrannasaurus Rex") , ("leastFavoriteAnimal","Bambi")] \$ "myFavoriteAnimalBase"
The rendered page: my favorite animal
The template: templates/myFavoriteAnimalBase.st
A template included from inside an included templates: leastFavoriteAnimal()

Try to gain an understanding of the most important features in the StringTemplate system by getting a sense of how the my-favorite-animal page got generated.

When you're done doing that, you should have enough StringTemplate knowledge to shoot yourself in the foot :)

For a more in depth look at StringTemplate, see the following:

And now, on to macid.