Generate: slugs with numbers break generation

[jiegillet]

Hi!
I was trying to do the equivalent of this PR in the Elm track, but I ran into an issue.
We have concepts named basics-1 and basics-2, which makes configlet generate break.

For the concept exercise lucians-luscious-lasagna, I wrote the introduction.md.tpl as

# Introduction

%{concept: basics-1}

But after generation the introduction.md is

# Introduction

1}

The culprit probably is

configlet/src/generate/generate.nim

Lines 100 to 102 in d31e569

	if scanp(content, i,
	"%{", *{' '}, "concept", *{' '}, ':', *{' '},
	+{'a'..'z', '-'} -> conceptSlug.add($_), *{' '}, '}'):

It seems that it would be easy enough to support numbers, is that an option?

[ee7]

Good catch - thanks.

It seems that it would be easy enough to support numbers, is that an option?

Yes, I believe we should do this.

In lint.md we specify that:

The "concepts[].slug" value must be a kebab-case string² with length <= 255

and that a kebab-case string can contain digits:

kebab-case string: a string that contains only characters in the range [a-z0-9], optionally separated by dashes (e.g. "two-fer"). It must match the regular expression: ^[a-z0-9]+(-[a-z0-9]+)*$

So configlet generate should support a concept slug that contains a digit in the placeholder.