# Difference between revisions of "Singleton list confusion"

From HaskellWiki

m |
(link to list notation) |
||

Line 1: | Line 1: | ||

Why do Haskell newcomers frequently believe, that list variables must be enclosed in brackets? |
Why do Haskell newcomers frequently believe, that list variables must be enclosed in brackets? |
||

People sometimes write argument patterns like <hask>[x]</hask>, hoping that <hask>x</hask> will assume all values of a list successively. |
People sometimes write argument patterns like <hask>[x]</hask>, hoping that <hask>x</hask> will assume all values of a list successively. |
||

− | Maybe |
+ | Maybe they expect some kind of [[list comprehension]]. |

+ | However, if there wouldn't be a special [[list notation]] and if there wouldn't be the special syntax for the list type constructor (thus we must write <hask>[a]</hask> instead of <hask>List a</hask>), |
||

+ | then there would be certainly less confusion. |
||

<!-- the first time I saw this in students homework solutions --> |
<!-- the first time I saw this in students homework solutions --> |
||

## Revision as of 07:07, 11 April 2008

Why do Haskell newcomers frequently believe, that list variables must be enclosed in brackets?
People sometimes write argument patterns like `[x]`

, hoping that `x`

will assume all values of a list successively.
Maybe they expect some kind of list comprehension.
However, if there wouldn't be a special list notation and if there wouldn't be the special syntax for the list type constructor (thus we must write `[a]`

instead of `List a`

),
then there would be certainly less confusion.

See for example Haskell-Cafe about testing for same characters in lists of strings, Pattern match failure