Data.HashMap有問題 - 無法插入值

Question

我真的是Haskell的新手，我對Data.HashMap有嚴重問題。我做錯了什麼？

這是我曾嘗試：

> ghci -v 
GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help 
Glasgow Haskell Compiler, Version 6.12.1, for Haskell 98, stage 2 booted by GHC version 6.12.1 
Using binary package database: /usr/lib/ghc-6.12.1/package.conf.d/package.cache 
Using binary package database: /home/joni/.ghc/x86_64-linux-6.12.1/package.conf.d/package.cache 
package utf8-string-0.3.4-15837bafc9579c596819d4381db0f19b is shadowed by package utf8-string-0.3.4-75a948ddecbeae79ab3ec3d9f9bcdb65 
package vimirc-0.0.0.1-d41d8cd98f00b204e9800998ecf8427e is unusable due to missing or recursive dependencies: 
    utf8-string-0.3.4-15837bafc9579c596819d4381db0f19b 
hiding package base-3.0.3.2 to avoid conflict with later version base-4.2.0.0 
hiding package bytestring-0.9.1.5 to avoid conflict with later version bytestring-0.9.1.10 
wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-9d35c97e886f807a1e6d024aaa91dcec 
wired-in package integer-gmp mapped to integer-gmp-0.2.0.0-9a51ffb34a83618a1a3d4e472b9977a0 
wired-in package base mapped to base-4.2.0.0-2cc27b7e43511c4ca001642a7f77a8f6 
wired-in package rts mapped to builtin_rts 
wired-in package haskell98 mapped to haskell98-1.0.1.1-0fdaf3b26bc38c43ce8371edf538dbf6 
wired-in package template-haskell mapped to template-haskell-2.4.0.0-bbc7c61990d2fe9d20be2deb924f833c 
wired-in package dph-seq mapped to dph-seq-0.4.0-52cfd6db5fc09a2abf793cd6a856a392 
wired-in package dph-par mapped to dph-par-0.4.0-b4f339fed900d7bc4b3db61526caf863 
Hsc static flags: -static 
Loading package ghc-prim ... linking ... done. 
Loading package integer-gmp ... linking ... done. 
Loading package base ... linking ... done. 
Prelude> t <- Data.HashTable.new (==) Data.HashTable.hashString 
*** Parser: 
*** Desugar: 
*** Simplify: 
*** CorePrep: 
*** ByteCodeGen: 
Prelude> Data.HashTable.insert t "Joni" 1 
*** Parser: 

<interactive>:1:31: 
    No instance for (Num GHC.Prim.Any) 
     arising from the literal `1' at <interactive>:1:31 
    Possible fix: add an instance declaration for (Num GHC.Prim.Any) 
    In the third argument of `Data.HashTable.insert', namely `1' 
    In the expression: Data.HashTable.insert t "Joni" 1 
    In the definition of `it': it = Data.HashTable.insert t "Joni" 1 

Prelude> Data.HashTable.insert t "Joni" "1" 
*** Parser: 

<interactive>:1:31: 
    Couldn't match expected type `GHC.Prim.Any' 
      against inferred type `[Char]' 
    In the third argument of `Data.HashTable.insert', namely `"1"' 
    In the expression: Data.HashTable.insert t "Joni" "1" 
    In the definition of `it': it = Data.HashTable.insert t "Joni" "1" 

Answer 1

你必須告訴它要在哈希表來存儲哪種類型。這個工程：

t <- Data.HashTable.new (==) Data.HashTable.hashString :: IO (Data.HashTable.HashTable String Integer) 
Data.HashTable.insert t "Joni" 1