Re: Learning the match-syntax...

[swedebugia <swedebugia@riseup.net>]

Hej :)

On 2019-01-06 22:36, Chris Marusich wrote:
> swedebugia@riseup.net writes:
> 
>> I'm trying very hard to learn the guile match-syntax.
> 
> When I first learned about "match", I found the Guile documentation to
> be insufficient.  It is good as a reference, though.
> 
> I recommend looking beyond the Guile reference manual for a tutorial.
> Check the Guile source for "match" related things. 

Good idea.

> Also, look at
> introductions to "match" from other Schemes, such as Racket.  I think
> you will understand it better by doing that.
> 

Thanks I already did that actually. The Racket guide was way better but 
not enough. Now I finally crossed the threshold to partially 
understanding it.

e.g.
(match '(1 2 "y" "x")
   (1
    'one)
   (number
    'number))

Will match any number for the first clause and any string for the 
second. It ONLY checks if it is a number.

To actually match something e.g. the "x" literally we need to nest the 
match like this:

(match '(1 2 y x)
   (string
    (match string
	("x"
           'x!)))
   (number
    'number))

Positional arguments work like this:

(match '(1 2 y x)
   ;match the third item
   (_ _ string
    ;check if it is the literal "x"
    (match string
	("x"
           'x!)))
   (number
    'number))

Correct?

-- 
Cheers Swedebugia