Create new bounded number data types in Haskell












0















I need to create a data type, that represents only the real numbers between 0 and 1. How would i go about that? Expected Behavior:



0 :: DataType        ===> DataType 0
(-1) :: DataType ===> Error









share|improve this question




















  • 6





    You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

    – chi
    Nov 22 '18 at 14:38











  • @chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

    – Carl
    Nov 22 '18 at 14:50











  • @Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

    – chi
    Nov 22 '18 at 15:12








  • 1





    Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

    – chi
    Nov 22 '18 at 15:16






  • 1





    Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

    – Luis Morillo
    Nov 23 '18 at 8:49


















0















I need to create a data type, that represents only the real numbers between 0 and 1. How would i go about that? Expected Behavior:



0 :: DataType        ===> DataType 0
(-1) :: DataType ===> Error









share|improve this question




















  • 6





    You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

    – chi
    Nov 22 '18 at 14:38











  • @chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

    – Carl
    Nov 22 '18 at 14:50











  • @Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

    – chi
    Nov 22 '18 at 15:12








  • 1





    Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

    – chi
    Nov 22 '18 at 15:16






  • 1





    Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

    – Luis Morillo
    Nov 23 '18 at 8:49
















0












0








0








I need to create a data type, that represents only the real numbers between 0 and 1. How would i go about that? Expected Behavior:



0 :: DataType        ===> DataType 0
(-1) :: DataType ===> Error









share|improve this question
















I need to create a data type, that represents only the real numbers between 0 and 1. How would i go about that? Expected Behavior:



0 :: DataType        ===> DataType 0
(-1) :: DataType ===> Error






haskell types numbers






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 22 '18 at 15:13









chi

74.1k284140




74.1k284140










asked Nov 22 '18 at 14:27









AgilixAgilix

11711




11711








  • 6





    You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

    – chi
    Nov 22 '18 at 14:38











  • @chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

    – Carl
    Nov 22 '18 at 14:50











  • @Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

    – chi
    Nov 22 '18 at 15:12








  • 1





    Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

    – chi
    Nov 22 '18 at 15:16






  • 1





    Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

    – Luis Morillo
    Nov 23 '18 at 8:49
















  • 6





    You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

    – chi
    Nov 22 '18 at 14:38











  • @chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

    – Carl
    Nov 22 '18 at 14:50











  • @Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

    – chi
    Nov 22 '18 at 15:12








  • 1





    Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

    – chi
    Nov 22 '18 at 15:16






  • 1





    Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

    – Luis Morillo
    Nov 23 '18 at 8:49










6




6





You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

– chi
Nov 22 '18 at 14:38





You could write an instance Num DataType and define fromInteger so that it errors out on invalid values. I'm not sure if that's a good idea, but it's the only way to achieve your goal.

– chi
Nov 22 '18 at 14:38













@chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

– Carl
Nov 22 '18 at 14:50





@chi I actually suspect a transcription error there, given that it's ascribing function types to literals. Not impossible, but I suspect that it's actually about creating a function to behave in such a way.

– Carl
Nov 22 '18 at 14:50













@Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

– chi
Nov 22 '18 at 15:12







@Carl I'm pretty sure the above -> represents "evaluates to", not function arrow. My comment assumed that interpretation, otherwise the question makes no sense. I'm now replacing them with ==> to avoid confusion.

– chi
Nov 22 '18 at 15:12






1




1





Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

– chi
Nov 22 '18 at 15:16





Beyond instance Num DataType, for real numbers we would also need instance Fractional DataType, and define a partial fromRational to reject invalid numbers.

– chi
Nov 22 '18 at 15:16




1




1





Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

– Luis Morillo
Nov 23 '18 at 8:49







Have you considered using smart constructors. Might by a good idea here. wiki.haskell.org/Smart_constructors

– Luis Morillo
Nov 23 '18 at 8:49














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